If the cause of above problem is based on different compiler (because I am using visual studio 2005, but I think the smilenet.dll is made on visual studio 2003 right??), the only solution is to rebuild smilenet.dll in my development environment?
I can create console or WinForms app in VS 2005, add the reference to Smile.NET (the public binaries, compiled with VS 2003 and available on our download page) and run the program which creates Smile.Network object and calls its methods.
What's the type of your project? Is it a webforms app?