I have a Matrix4x4 template class in a header file. I've read that templates need to be only in headers (source: http://stackoverflow.com/questions/495021/why-can-templates-only-be-implemented-in-the-header-file). Now, my problem is that when I change my header's code by adding a function and that I use this method somewhere (in main() in my case), then the compiler tells me my class Matrix4x4 doesn't contain the function. I thought that doing a rebuild would correct this error, but it doesn't work. Do you have any idea what I could do to fix this error?