diff --git a/src/optimization/CasADiIterCallback.h b/src/optimization/CasADiIterCallback.h
index dc2a0a1c..fa8e9240 100644
--- a/src/optimization/CasADiIterCallback.h
+++ b/src/optimization/CasADiIterCallback.h
@@ -14,7 +14,7 @@ class CasADiIterCallback : public Callback {
   ~CasADiIterCallback() override {}
 
   // Number of inputs and outputs
-  casadi_int get_n_in() override { return 1;}
+  casadi_int get_n_in() override { return 5;}
   casadi_int get_n_out() override { return 1;}
 
   // Initialize the object
@@ -24,8 +24,7 @@ class CasADiIterCallback : public Callback {
 
   // Evaluate numerically
   std::vector<DM> eval(const std::vector<DM>& arg) const override {
-    DM x = arg.at(0);
-    DM f = sin(d*x);
-    return 1;
+    std::cout << "eval" << std::endl;
+    return {1};
   }
 };
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