Any error in second cpp file not recognised

I have 1 header file and 2 .cpp files (I've included main.cpp) and work on CodeBlocks. My problem is that compiler not see the errors in the second .cpp file (graph_interface.cpp) when I build it. Do you have any suggestions? Where am I going wrong?.

Simply I get the output even I did the wrong thing in graph_implementation.cpp file:

 Target is up to date.
 Nothing to be done (all items are up-to-date).

For example, my code in main.cpp

//main.cpp
#include "graph_interface.h"

int main(int argc,char *argv[])
   {
     return 0;
   }

graph_interface.h file

  #ifndef GRAPH_INTERFACE_H_INCLUDED
  #define GRAPH_INTERFACE_H_INCLUDED

  typedef struct{int v;int w;} Edge;
  Edge EDGE(int,int);

  typedef struct graph *Graph;
  Graph GRAPHinit(int);
  void GRAPHinsertE(Graph,Edge);
  void GRAPHremoveE(Graph,Edge);
  int GRAPHedges(Edge[],Graph G);
  Graph GRAPHcopy(Graph);
  void GRAPHdestroy(Graph);
  #endif // GRAPH_INTERFACE_H_INCLUDED

And other cpp file graph_implementation.cpp

 #include "graph_interface.h"
 using namespace std;
 struct graph{
   int V;
   int E;
   int **adj;
 };
 Graph GRAPHinit(int V){
 Graph G=malloc(sizeof *G);
    G->V=V;
    G->E=0;
    G->adj=MATRIXint(V,V,0);
    return G;
    ;// not give anything
 }