Accessing structured storage pointer

Dear Sir,
I am trying to get IStorage pointer of an object store but i am unable to do that thing . I wrote following code to get IStorage interface pointer But it is not working any body can help me to sort out this problem .

char *FileName;
FileName=new char;
strcpy(FileName,"hpc.obs");
IStorage **pStorage;
if(StgOpenStorage((LPCTSTR)FileName,NULL,STGM_READ|STGM_WRITE|STGM_SHARE_DENY_WRITE,NULL,0,pStorage)==S_OK)
{
AfxMessageBox(CString("Able to open Object store"));
}
else
DWORD error=GetLastError();

In this code it goes to else part and gives error code 0.I checked StgOpenStorage with all possible return values but it is going in else part.
Your suggestion will be very appreciable.
Thanking in advance
Sanjeev