GetResponseEx / GetCommandResponseEx issue

Hi! I cannot send a command to PMAC. I have a memory error each time I execute this part of code:

/*Send command to PMAC*/

BSTR question = SysAllocString(L"CPU");

BSTR answ;

long err;

pmacDevice.GetResponseEx(dwDevice,question,0,&answ,&err);

I use Visual studio 2010 and I'm using the pmacdevice.h and pmacdevice.cpp files obtained from the Pcomm32.exe (with Visual C++ 6, using the procedure described in the PcommServer manual).

The error is the following:

Unhandled exception at 0x761d46b1 in WinPmacInterface.exe: 0xC0000005: Access violation reading location 0xccccccc8.

Do you have any suggestion?