The inefficiency of the Physical Optics (PO) approach for diffraction problems is proven with two examples. Then, Stratton's formulation to find the fields in a volume V is introduced to complement the PO approach. Thus, both of these examples yielded correct results. This new method is applied to perfectly conducting wedges and to lossless dielectric wedges. The solutions obtained are compared with the solutions, which were obtained with integral equations and they are found to be very satisfactory.