一个DLL中的EntryPointNotFoundException，而在另一个DLL中似乎很好

Question

I have two DLLs that I created and they reside in Assets/Plugins. One seems to be working fine, the other gives me an EntryPointNotFoundException even though the code look exactly the same to me. Maybe there's some setting I missed in VisualStudio? What settings do I need?

The one that works looks like this:

C#

[DllImport("winBlinkDetect")]
     private static extern void IsSeven(ref int x);

 [DllImport("winBlinkDetect")]
     private static extern int PrintFive();

 void Start()
     {
         int test = 0;
         Debug.Log("x = " + test);
         IsFive(ref test);
         Debug.Log("x = " + test);
         Debug.Log(PrintFive());
     }

C++ Header

 #if _MSC_VER // this is defined when compiling with Visual Studio
 #define EXPORT_API __declspec(dllexport) // Visual Studio needs annotating exported functions with this
 #define _USE_MATH_DEFINES
 #else
 #define EXPORT_API // XCode does not need annotating exported functions, so define is empty
 #endif

 #ifdef __cplusplus
 extern "C" {
 #endif

     void EXPORT_API IsFive(int *y);
     void EXPORT_API IsSeven(int *x);
     int EXPORT_API PrintFive();


 #ifdef __cplusplus
 }
 #endif
C++ .cpp

 void IsFive(int *y)
 {
     *y = 5;
 }

 void IsSeven(int *x)
 {
     *x = 7;
 }

 int PrintFive()
 {
     return 99;
 }

For the one that doesn't work: C#

[DllImport("brain")]
     private static extern int GiveNinetyNine();

     [DllImport("brain")]
     private static extern void IsFive(ref int x);

 void Start()
     {
         int test = 0;
         Debug.Log("x = " + test);
         IsFive(ref test);
         Debug.Log("x = " + test);
         Debug.Log(GiveNinetyNine());
     }

C ++ Header

#if _MSC_VER // this is defined when compiling with Visual Studio
 #define EXPORT_API __declspec(dllexport) // Visual Studio needs annotating exported functions with this
 #define _USE_MATH_DEFINES
 #else
 #define EXPORT_API // XCode does not need annotating exported functions, so define is empty
 #endif

 #include <string>;

 #ifdef __cplusplus
 extern "C" {
 #endif

     // test functions
     void EXPORT_API IsFive(int *y);
     void EXPORT_API IsSeven(int *x);
     int EXPORT_API GiveNinetyNine();
 #ifdef __cplusplus
 }
 #endif
C++ .cpp

 void IsFive(int *y)
 {
     *y = 5;
 }

 void IsSeven(int *x)
 {
     *x = 7;
 }

 int GiveNinetyNine()
 {
     return 99;
 }

Answer 1

Dependency Walker shows no exported functions, but exported functions in header file looks good. Seems the h file is not included into the cpp file. To check this put __declspec(dllexport) inside cpp in function definition.