vc dll文件中函数返回值在vb中调用出现异常？

#include <windows.h>


#include "7012Demo.h"

#include "Isa7012.h"

#pragma comment(lib, "ISA7012DLL.lib")



BOOL IsIniSuccess = FALSE ;

BOOL Ini7012(DWORD hwnd)


{

AD7012_WINCTRL_STRUCT ddd;

memset( &ddd, 0, sizeof(AD7012_WINCTRL_STRUCT) );

ddd.m_ADType = 1;

ddd.m_BufferBlock = 4;

ddd.m_ClkSrc = 0;

ddd.m_EndChn = 15;

ddd.m_hWnd = hwnd;

ddd.m_StartChn = 0;

ddd.m_StartType = 0;

ddd.m_Timer0Val = 200;

ddd.m_Timer1Val = 20;

ddd.m_Timer2Val = 20;

//ddd.m_IntFlag = 0;






if ( Isa7012_Open(0) )


{

//设备已成功打开



}


else

{

return FALSE;

}

if ( Isa7012_IsOpen(0) )

{

//打开Isa7012



}

else

{

return FALSE;

}

if ( Isa7012_ADCtrl(0 , &ddd))

{

//初始化正确



}

else

{

return FALSE;

}

Isa7012_StartAD(0);

}




//int WINAPI DllMain (HINSTANCE hInstance, DWORD fdwReason, PVOID pvReserved)

//{

//return TRUE ;

//}



__stdcall int CALLBACK Compare (int a,int b)


{

if(a>=b)

return a;

else

return b;

};

__stdcall float CALLBACK Friction (DWORD hwnd)

{

if ( !IsIniSuccess )

{

if (Ini7012(hwnd))

{

IsIniSuccess = TRUE ;

}

else

{

IsIniSuccess = FALSE ;

return 110;

}

}



float volL = 0.0f;


WORD dddd;

if(!Isa7012_SoftADGetVal(0,4,&dddd))

{

return -50;

}

volL = dddd & 0xFFF;

volL=((volL / 4095 * 20 - 3) * 100 / 15);

return volL;

};

下面是在vb中的程序：大家帮忙看看什么情况

Private Declare Function Friction Lib "C:\Documents and Settings\Administrator\桌面\dllvbdemo\7012Demo.dll" _

() As Long

Private Declare Function Compare Lib "C:\Documents and Settings\Administrator\桌面\dllvbdemo\7012Demo.dll" _

(ByVal CompareA As Integer, ByVal CompareB As Integer) As Integer

Dim i As Single

Private Sub Form_Load() '窗体加载

i = Friction()

End Sub

在vc中返回值volL为46.2542
在vb中获得的值为36