C++ A nonstatic member reference must be relative to a specific object

    Vector2D tankPos = Tank_b017191c::GetTankPosition();

I am trying to call a function from a different class but I am getting this error:

'47 IntelliSense: a nonstatic member reference must be relative to a specific object    e:\Repos\GameAI\GameAI\PathFinder_b017191c.cpp  113 21  GameAI'

I have included Tank_b017191c.h in my header file but not getting very far..