Problems with using VarPtr function

From VB project I call to method of ActiveX DLL written in C++.
The parameter is long (address in memory) received by using VarPtr function in VB (address of long variable ).
When I change the value of variable in C++ by received address (the address is correct) I dont get in VB correct result.
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VB code:

Dim MyObj As New NUMBERSTESTLib.CheckParams
Dim i as Long
MyObj.FunCheckParams VarPtr(i), StrPtr(str1)

C++ code:

STDMETHODIMP CheckParams::FunCheckParams(long iNumber, long sString)
{

long *intNumber = (long *)iNumber;

wchar_t *intString = (wchar_t *)sString; //Unicode converting

*intNumber = 33;
wcscpy(intString,_T("Test"));

return S_OK;
}
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I want to get to my long variable defined in VB (i) the value that set in C++ (33)...

Functions VarPtr,StrPtr,ObjPtr are not documented and supported by Microsoft...
May be anybody has good samples of code how to use them?