  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 \textsl{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 Painleve
coordinates: also in this procedure it was missed the temporal factor
contribution. In this way it is naturally solved also the "factor-two-problem".
