diff --git a/libraries/report/src/Report/Report.cpp b/libraries/report/src/Report/Report.cpp
index f5fb305..d7f28eb 100644
--- a/libraries/report/src/Report/Report.cpp
+++ b/libraries/report/src/Report/Report.cpp
@@ -3,8 +3,6 @@
 #include <common/global.hpp>
 #include <boost/foreach.hpp>
 
-static const std::string kReport = "report";
-
 namespace report_generator
 {
 
@@ -12,28 +10,32 @@ Report::Report()
 {
 }
 
-Report::Report( const ReportTree& reportTree )
-	: _basicElementTree( reportTree )
-{
-}
-
 Report::~Report()
 {
 }
 
-
-void Report::addBasicElement( std::shared_ptr< be::Element > element )
+ReportNode Report::addFirstElement( std::shared_ptr< be::Element > element )
 {
-	ReportTree tmpTree;
-	tmpTree.add( toKey( element->getUniqueId() ), element );
-	_basicElementTree.add_child( kReport + ".", tmpTree );
+	if( getSize() > 0 )
+	{
+		LOG_WARNING( "addFirstElement: first node already exist.");
+	}
+	else
+	{
+		ReportTree tree;
+		tree.add( toKey( getSize() ), element );
+		_basicElementTree.add_child( kReport + ".", tree );
+	}
+	return getFirstNode();
 }
 
 ReportNode Report::getFirstNode()
 {
 	try
 	{
-		return ReportNode( getBegin(), 0, getSize() );
+		if( getSize() == 0 )
+			throw std::runtime_error( "getFirstNode: empty tree." );
+		return ReportNode( getBegin(), 0, &_basicElementTree );
 	}
 	catch( const std::runtime_error& e )
 	{
@@ -44,11 +46,23 @@ ReportNode Report::getFirstNode()
 
 ReportIterator Report::getBegin()
 {
-	return _basicElementTree.get_child( kReport ).begin();
+	try
+	{
+		if( getSize() == 0 )
+			throw std::runtime_error( "getBegin: empty tree." );
+		return _basicElementTree.get_child( kReport ).begin();
+	}
+	catch( const std::runtime_error& e )
+	{
+		LOG_ERROR( e.what() );
+		throw;
+	}
 }
 
 size_t Report::getSize()
 {
+	if( _basicElementTree.empty() )
+		return 0;
 	return _basicElementTree.get_child( kReport ).size();
 }
 
diff --git a/libraries/report/src/Report/Report.hpp b/libraries/report/src/Report/Report.hpp
index 636f3d2..3643947 100644
--- a/libraries/report/src/Report/Report.hpp
+++ b/libraries/report/src/Report/Report.hpp
@@ -16,13 +16,10 @@ class Report
 {
 public:
 	Report();
-	Report( const ReportTree& reportTree );
 	~Report();
 
-	void addBasicElement( std::shared_ptr< be::Element > element );
-
+	ReportNode addFirstElement( std::shared_ptr< be::Element > element );
 	ReportNode getFirstNode();
-
 	ReportIterator getBegin();
 	size_t getSize();
 	
diff --git a/libraries/report/tests/reportTests.hpp b/libraries/report/tests/reportTests.hpp
index fd100c7..78a55e7 100644
--- a/libraries/report/tests/reportTests.hpp
+++ b/libraries/report/tests/reportTests.hpp
@@ -5,87 +5,58 @@ BOOST_AUTO_TEST_CASE( report_report )
 {
 	LOG_INFO( ">>> report_report <<<" );
 	{
-		LOG_INFO( ">>> report_report <<<" );
 		Report report;
 
 		std::shared_ptr< ben::Number< int > > numPtr1( new ben::Number< int > );
-		std::shared_ptr< ben::Number< int > > numPtr2( new ben::Number< int > );
 		std::shared_ptr< bed::Data > dataPtr( new bed::Data );
-		report.addBasicElement( numPtr1 );
-		report.addBasicElement( dataPtr );
-		report.addBasicElement( numPtr2 );
 
-		BOOST_CHECK_EQUAL( report.getSize(), 3 );
-
-		ReportNode node = report.getFirstNode();
-		BOOST_CHECK_EQUAL( node.getIndex(),      0 );
-		BOOST_CHECK_EQUAL( node.getIndexTotal(), 3 );
-		BOOST_CHECK_EQUAL( node.getElementPointer()->getType(), be::Element::eTypeNumber );
-
-		node = node.next();
-		BOOST_CHECK_EQUAL( node.getIndex(),      1 );
-		BOOST_CHECK_EQUAL( node.getIndexTotal(), 3 );
-		BOOST_CHECK_EQUAL( node.getElementPointer()->getType(), be::Element::eTypeData );
-
-		node = node.next();
-		BOOST_CHECK_EQUAL( node.getIndex(),      2 );
-		BOOST_CHECK_EQUAL( node.getIndexTotal(), 3 );
-		BOOST_CHECK_EQUAL( node.getElementPointer()->getType(), be::Element::eTypeNumber );
+		BOOST_CHECK_EQUAL( report.getSize(), 0 );
+		
+		ReportNode node1 = report.addFirstElement( numPtr1 );
+		BOOST_CHECK_EQUAL( report.getSize(), 1 );
+		BOOST_CHECK_EQUAL( node1.getIndex(), 0 );
+		
+		ReportNode node2 = report.addFirstElement( dataPtr );
+		BOOST_CHECK_EQUAL( report.getSize(), 1 );
+		BOOST_CHECK_EQUAL( node2.getIndex(), 0 );
 	}
 	{
-		ReportTree tree;
-		ReportTree group;
-		ReportTree node1, node2, node3, node4, node5;
-		std::shared_ptr< ben::Number< int > >  numPtr1( new ben::Number< int > );
-		std::shared_ptr< ben::Number< int > >  numPtr2( new ben::Number< int > );
-		std::shared_ptr< bed::Data >          dataPtr1( new bed::Data );
-		std::shared_ptr< bed::Data >          dataPtr2( new bed::Data );
-		std::shared_ptr< bed::Data >          dataPtr3( new bed::Data );
-
-		node1.add( "0", ( std::shared_ptr< be::Element > )  numPtr1 );
-		node2.add( "1", ( std::shared_ptr< be::Element > )  numPtr2 );
-		node3.add( "2", ( std::shared_ptr< be::Element > ) dataPtr1 );
-		node4.add( "3", ( std::shared_ptr< be::Element > ) dataPtr2 );
-		node5.add( "4", ( std::shared_ptr< be::Element > ) dataPtr3 );
-
-		node2.add_child( "group.", node5 );
-		
-		tree.add_child( "report.", node1 );
-		tree.add_child( "report.", node2 );
-		tree.add_child( "report.", node3 );
-		tree.add_child( "report.", node4 );
-
-		Report report( tree );
-
-		BOOST_CHECK_EQUAL( report.getSize(), 4 );
-
-		ReportNode node = report.getFirstNode();
-		BOOST_CHECK_EQUAL( node.getIndex(),      0 );
-		BOOST_CHECK_EQUAL( node.getIndexTotal(), 4 );
-		BOOST_CHECK_EQUAL( node.getElementPointer()->getType(), be::Element::eTypeNumber );
-
-		node = node.next();
-		BOOST_CHECK_EQUAL( node.getIndex(),      1 );
-		BOOST_CHECK_EQUAL( node.getIndexTotal(), 4 );
-		BOOST_CHECK_EQUAL( node.getElementPointer()->getType(), be::Element::eTypeNumber );
+		Report report;
+		BOOST_CHECK_EQUAL( report.getSize(), 0 );
+		BOOST_CHECK_THROW( report.getFirstNode(), std::runtime_error );
+		BOOST_CHECK_THROW( report.getBegin(), std::runtime_error );
+	}
+}
 
-		ReportNode child = node.firstChild();
-		BOOST_CHECK_EQUAL( child.getIndex(),      0 );
-		BOOST_CHECK_EQUAL( child.getIndexTotal(), 1 );
-		BOOST_CHECK_EQUAL( child.parent()->getIndex(),      1 );
-		BOOST_CHECK_EQUAL( child.parent()->getIndexTotal(), 4 );
-		BOOST_CHECK_EQUAL( child.getElementPointer()->getType(), be::Element::eTypeData );
+BOOST_AUTO_TEST_CASE( report_report_and_node_report )
+{
+	LOG_INFO( ">>> report_report_and_node_report <<<" );
+	{
+		Report report;
 
-		node = child.parent()->next();
-		BOOST_CHECK_EQUAL( node.getIndex(),      2 );
-		BOOST_CHECK_EQUAL( node.getIndexTotal(), 4 );
-		BOOST_CHECK_EQUAL( node.getElementPointer()->getType(), be::Element::eTypeData );
+		std::shared_ptr< ben::Number< int >   > numPtr1( new ben::Number< int > );
+		std::shared_ptr< bed::Data            > dataPtr( new bed::Data );
+		std::shared_ptr< ben::Number< short > > numPtr2( new ben::Number< short > );
 
-		node = node.next();
-		BOOST_CHECK_EQUAL( node.getIndex(),      3 );
-		BOOST_CHECK_EQUAL( node.getIndexTotal(), 4 );
-		BOOST_CHECK_EQUAL( node.getElementPointer()->getType(), be::Element::eTypeData );
-		BOOST_CHECK_THROW( node.parent(), std::runtime_error );
+		BOOST_CHECK_EQUAL( report.getSize(), 0 );
+		
+		ReportNode node1 = report.addFirstElement( numPtr1 );
+		BOOST_CHECK_EQUAL( report.getSize(), 1 );
+		BOOST_CHECK_EQUAL( node1.getIndex(), 0 );
+		BOOST_CHECK_EQUAL( node1.getSecond()->begin()->first, "0" );
+		BOOST_CHECK_THROW( node1.parent(), std::runtime_error );
+		
+		node1 = node1.appendNext( dataPtr );
+		BOOST_CHECK_EQUAL( report.getSize(), 2 );
+		BOOST_CHECK_EQUAL( node1.getIndex(), 1 );
+		BOOST_CHECK_EQUAL( node1.getSecond()->begin()->first, "1" );
+		BOOST_CHECK_THROW( node1.parent(), std::runtime_error );
+
+		ReportNode child1 = node1.appendChild( numPtr2 );
+		BOOST_CHECK_EQUAL( report.getSize(), 2 );
+		BOOST_CHECK_EQUAL( child1.getIndex(), 0 );
+		BOOST_CHECK_EQUAL( child1.getSecond()->begin()->first, "1-0" );
+		BOOST_CHECK_EQUAL( child1.parent()->getSecond()->begin()->first, "1" );
 	}
 }