diff --git a/Assets/QuickSheet/Editor/BaseMachineEditor.cs b/Assets/QuickSheet/Editor/BaseMachineEditor.cs
index 91433ef..80fa36f 100644
--- a/Assets/QuickSheet/Editor/BaseMachineEditor.cs
+++ b/Assets/QuickSheet/Editor/BaseMachineEditor.cs
@@ -7,9 +7,10 @@
 ///////////////////////////////////////////////////////////////////////////////
 using UnityEngine;
 using UnityEditor;
+using System;
+using System.IO;
 using System.Collections;
 using System.Collections.Generic;
-using System.IO;
 
 namespace UnityQuickSheet
 {
@@ -28,6 +29,21 @@ protected virtual void Import(bool reimport = false)
             Debug.LogWarning("!!! It should be implemented in the derived class !!!");
         }
 
+        /// <summary>
+        /// Check the given header column has valid name which should not be any c# keywords.
+        /// </summary>
+        protected bool IsValidHeader(string s)
+        {
+            // no case sensitive!
+            string comp = s.ToLower();
+
+            string found = Array.Find(Util.Keywords, x => x == comp);
+            if (string.IsNullOrEmpty(found))
+                return true;
+
+            return false;
+        }
+
         /// <summary>
         /// Generate script files with the given templates.
         /// Total four files are generated, two for runtime and others for editor.
diff --git a/Assets/QuickSheet/ExcelPlugin/Editor/ExcelMachineEditor.cs b/Assets/QuickSheet/ExcelPlugin/Editor/ExcelMachineEditor.cs
index 518e0ae..30fe084 100644
--- a/Assets/QuickSheet/ExcelPlugin/Editor/ExcelMachineEditor.cs
+++ b/Assets/QuickSheet/ExcelPlugin/Editor/ExcelMachineEditor.cs
@@ -207,13 +207,28 @@ protected override void Import(bool reimport = false)
                 );
                 return;
             }
+
+            int startRowIndex = 0;
             string error = string.Empty;
-            var titles = new ExcelQuery(path, sheet).GetTitle(0, ref error);
+            var titles = new ExcelQuery(path, sheet).GetTitle(startRowIndex, ref error);
             if (titles == null || !string.IsNullOrEmpty(error))
             {
                 EditorUtility.DisplayDialog("Error", error, "OK");
                 return;
             }
+            else
+            {
+                // check the column header is valid
+                foreach(string column in titles)
+                {
+                    if (!IsValidHeader(column))
+                    {
+                        error = string.Format(@"Invalid column header name {0}. Any c# keyword should not be used for column header. Note it is not case sensitive.", column);
+                        EditorUtility.DisplayDialog("Error", error, "OK");
+                        return;
+                    }
+                }
+            }
 
             List<string> titleList = titles.ToList();
 
@@ -221,17 +236,17 @@ protected override void Import(bool reimport = false)
             {
                 var headerDic = machine.HeaderColumnList.ToDictionary(header => header.name);
 
-                // collect non changed header columns
+                // collect non-changed column headers
                 var exist = from t in titleList
                             where headerDic.ContainsKey(t) == true
-                            select new HeaderColumn { name = t, type = headerDic[t].type, OrderNO = headerDic[t].OrderNO };
+                            select new HeaderColumn { name = t, type = headerDic[t].type, isArray = headerDic[t].isArray, OrderNO = headerDic[t].OrderNO };
 
-                // collect newly added or changed header columns
+                // collect newly added or changed column headers
                 var changed = from t in titleList
                               where headerDic.ContainsKey(t) == false
                               select new HeaderColumn { name = t, type = CellType.Undefined, OrderNO = titleList.IndexOf(t) };
 
-                // merge two
+                // merge two list via LINQ
                 var merged = exist.Union(changed).OrderBy(x => x.OrderNO);
 
                 machine.HeaderColumnList.Clear();
diff --git a/Assets/QuickSheet/ExcelPlugin/Editor/ExcelQuery.cs b/Assets/QuickSheet/ExcelPlugin/Editor/ExcelQuery.cs
index c12a8b4..014cf02 100644
--- a/Assets/QuickSheet/ExcelPlugin/Editor/ExcelQuery.cs
+++ b/Assets/QuickSheet/ExcelPlugin/Editor/ExcelQuery.cs
@@ -219,13 +219,8 @@ public string[] GetTitle(int start, ref string error)
                     }
                     else
                     {
-                        if (IsValidHeader(value))
-                            result.Add(value);
-                        else
-                        {
-                            error = string.Format(@"Error at column {0}, {1} is invalid name as header column.", i, value);
-                            return null;
-                        }
+                        // column header is not an empty string, we check its validation later.
+                        result.Add(value);
                     }
                 }
 
@@ -236,21 +231,6 @@ public string[] GetTitle(int start, ref string error)
             return null;
         }
 
-        /// <summary>
-        /// Check the given header column has valid name which should not be any c# keywords.
-        /// </summary>
-        private bool IsValidHeader(string s)
-        {
-            // no case sensitive!
-            string comp = s.ToLower();
-
-            string found = Array.Find(Util.Keywords, x => x == comp);
-            if (string.IsNullOrEmpty(found))
-                return true;
-
-            return false;
-        }
-
         /// <summary>
         /// Convert type of cell value to its predefined type in the sheet's ScriptMachine setting file.
         /// </summary>
diff --git a/Assets/QuickSheet/GDataPlugin/Editor/GoogleMachineEditor.cs b/Assets/QuickSheet/GDataPlugin/Editor/GoogleMachineEditor.cs
index 21f25e1..a4111fc 100644
--- a/Assets/QuickSheet/GDataPlugin/Editor/GoogleMachineEditor.cs
+++ b/Assets/QuickSheet/GDataPlugin/Editor/GoogleMachineEditor.cs
@@ -220,6 +220,14 @@ protected override void Import(bool reimport = false)
                 if (int.Parse(m.Value) > 1)
                     return;
 
+                // check the column header is valid
+                if (!IsValidHeader(cell.Value))
+                {
+                    string error = string.Format(@"Invalid column header name {0}. Any c# keyword should not be used for column header. Note it is not case sensitive.", cell.Value);
+                    EditorUtility.DisplayDialog("Error", error, "OK");
+                    return;
+                }
+
                 HeaderColumn column = new HeaderColumn();
                 column.name = cell.Value;
                 if (headerDic != null && headerDic.ContainsKey(cell.Value))