Link DLL with Visual C++ not working

I have the following problem:
I have a dll compiled with MinGW and a header file that describes the DLL exports. I want to use this DLL in a Visual C++ projects. Since i don't have a LIB file and i don't want to use LoadLibrary function i created a DEF file. The contents of the EXPORTS section of the DEF file i toke from DUMPBIN /EXPORTS [the_dll], so it should be ok.
After i created the lib file i included it in my Visual C++ project and the project has compiled successfully. But when i executed it, the application crashed. This application is working when compiled with GCC and the same DLL.
So is the problem somewhere in MinGW or what?
May be i must pass some special parameters to cl.exe or link.exe
Experts please help!

In more details:
So in the header file i have a definition of an abstract class wich has onlu pure virtual methods.
In the DLL i have only one export function which is returning a pointer to an instance of this class or more precisely some class that inherits this abstract class.
The program is something like:

Code:

---

SomeClass* c = ImportedMethod();
c->someMethod(); // Here the program crashes

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It looke strange i know, the problem is that i don't hava the source of the DLL neither i have any more information about it. Only those header:

Code:

---

class SomeClass
{
public:
virtual void someMethod() = 0;
}
extern "C"
__declspec (dllexport) SomeClass * ImportedMethod();

---

I think you might have to make your function stdcall

Code:

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virtual void WINAPI someMethod() = 0;

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No, this doesn't work. The error is that the calling convention is wrong so it's definitely not stdcall

Well. This worked for me:

VC6 main.cpp

Code:

---

int main()
{
        HMODULE h =
                ::LoadLibrary("C:\\Development\\Dev\\Project1.dll");

        if(!h) return 0;

        SomeClass* (*t)() =
                (SomeClass* (*)()) ::GetProcAddress(h, "ImportedMethod");

        if(!test) return 0;

        SomeClass * someClass = (*t)();
        someClass->someMethod();

        return 0;
}

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Dev C++ 4.9.9.2 dll.h

Code:

---

#ifndef _DLL_H_
#define _DLL_H_

#include <iostream>

class SomeClass
{
public:
      virtual void someMethod() = 0;
};

class RawrClass : public SomeClass
{
public:
      virtual void someMethod() { std::cout << "Test"; }
};

extern "C" __declspec (dllexport) SomeClass * ImportedMethod();


#endif

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Dev C++ 4.9.9.2 dllmain.cpp

Code:

---

#include "dll.h"
#include <windows.h>

SomeClass * ImportedMethod()
{
          return new RawrClass();
}

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