>>>You're passing strings by reference for parameters DECLAREd as passed by value.
>>>
>>
>>Just tried that (removing the @) and the same thing happens :(
>
>It wasn't my point. You've first properly declare parameters and than properly pass them. Do you've declaration for C++ or VB for this DLL? Can you post it?

from VB6:

Public Declare Function BUICScan& Lib "BUICAP32.DLL" (ByVal iJob&, ByVal lpFront$, ByVal FLen$, ByVal lpBack$, ByVal BLen$, ByVal LpCode$, ByVal LpLen$)