我用VC++做二次开发，怎么一直调用不到 Ptc.MathcadPrime.Automation.dll里的函数，下面这段代码有问题吗？
#include "stdio.h"
#include "windows.h"
#include "stdafx.h"typedef int(*AddFunc)();
int main()
{
AddFunc _AddFunc;
HINSTANCE hInstLibrary = LoadLibrary("Ptc.MathcadPrime.Automation.dll");
_AddFunc = (AddFunc)GetProcAddress(hInstLibrary, "Activate");
return 0;
}