pch doesn't seem to be used

[Pat]

Hi,

I have a Precomp.h header, in which the most used headers are #included, 
and, in the same directory, the compiled Precomp.h.gch

At the start of the compilation, the pch is read and verified correctly 
because when the options used to compile it are changed, the correct 
warning appears.( "warning: ./Precomp.h.gch: created with different flags" )
Immediately after that, the gch file is closed and the compiler starts 
to read the original headers files.

Any hint ?

Pat