Calling up a VB.NET function: We are trying to call up a function in a dll that we have written in VB.NET. This doesn't work. We tried the dll that you provide on your internet site which is written in C++; it worked without any problems. Do we need to do anything special for VB.NET dlls?

In contrast to the earlier VB technology (VB6) the VB.NET dlls cannot be called up without a .NET runtime, since the dll contains .NET pseudocode. So you either have to write a C++ wrapper that calls the VB.NET function using the Microsoft interoperability library. Or, with GuiXT Controls you can call the function as a "COM object" that you can generate from your VB.NET function in Visual Studio. Please see the GuiXT Controls tutorial 12 for an example.