LaTeX.org

I got a little Problem here.

I need to use a "#" in a Section Headline.

so i got
\newcommand{\FISs}{FIS\raisebox{2mm}{\tiny\#}}
and i want to put this in a section like
section{\FISs}

But i keek gettig the same Error over and over.
Errorinfo

! Argument of \@sect has an extra }.<inserted ...