Hi Everybody:
I've just found the workaround by myself. The problem seemed to be that I
loaded a lot of packages on the preamble and the order was not the correct one.
In fact, I was using the "fancyhdr" package. When I changed the order of both
packages, everuthyng worked fine. I had load "geometry" package first, and then
the "fancyhdr".
Thank you anyway.
