submitted 30/12/2008 The Hawking radiation in the semi-classical approach is re-considered. In the so-called “Angheben method ” for the calculation of the imaginary part of the action it was missed the temporal part contribution. This has been recently noticed by Akhmedov et al., but also there the time part was not properly considered, the sign being reversed. We show that using the semi-classical approach on a fixed background it is not possible to find any tunneling effect from the interior to the exterior of the Schwarzschild black hole. The same critic applies to the derivations which use the Painlevé coordinates: also in this procedure it was missed the temporal factor contribution. In this way it is naturally solved also the “factor-two-problem”.