Problem with templates

I have some (weird?) problem with a template class I'm writing. First, I have a template class called CTree for storing generic data. Then, I declare an instance of it. When I link the whole program, I get an error: external symbol not defined "public: int const __thiscall IcdTree::AddNode ... ".
What could that be? The method it references is defined, and the .cpp file is included in the project.

Thanks, Martin

Is the sourcecode of your templateclass written in the headerfile of your template ?

All the code for the template class itself is in the header file.
To specify the problem: I have a class template called CTree <T>, which implements a generic tree. In another class, say CXYTree, I instantiate it with a member variable:
CTree<struct Something> m_tMem.
The linker error occurs when I try to use a member of CXYTree in my document, e.g. CXYTree::AddNode(...). The linker then complains that the symbol CXYTree::AddNode(Something const &) is not defined.

You have to call the method of your member variable:

m_tMem.AddNode(...);