Looks like the typical error where you try to define the templates in a separate file. Declaration and definition cannot be separate; the full declaration of everything has to be visible at every point where the template is instantiated. Put the code for all your functions in the header file instead of in a separate file.

Looks like the typical error where you try to define the templates in a separate file. Declaration and definition cannot be separate; the full declaration everything has to be visible at every point where the template has to be instantiated. Put the code for all your functions in the header file instead of in a separate file.