How can an application load a DLL without its name?

Question

I have disassembled a VB6 application that calls a function in a DLL library, but I can't find any reference to the DLL in the disassembly. How can the calling code load this DLL? It is dynamically linked, as I can observe the effects of removing and replacing the DLL.

I'm using IDA Pro Free, the calling application is a VB6 app, and the DLL is a plain Win32 DLL that I suspect was created using C or C++.

Answer 1

What do you mean by "can't find any reference"? you don't see the string of the dll name? you don't see the code who calls the dll?
You can put a break point in the dll and see the callstack that leads to the VB6 app.

Answer 2

Open your application in PE Explorer, it will show you all the DLLs linked.

Answer 3

If it's a COM DLL, it may well be looking it up via GUID instead of name.

Answer 4

Have you searched for the Unicode version of the DLL name too? The application that loads the DLL might be built using wide characters.