GLSL shader problem

The objects show up, but only because the shader fails:

:display:gsg:glgsg(error): An error occurred while compiling shader!
ERROR: 0:8: 'p3d_Vertex' : undeclared identifier
ERROR: 0:8: 'assign' :  cannot convert from '4X4 matrix of float' to 'Position 4-component vector of float'