An xpm as buffer background

[cp]

Hi!

I am using GNU Emacs 21.[12].

I would like to set an image as buffer background.
So far I tried to set the x resource *.attributeStipple to the image path, and
tried the set-face-background-image lisp function with no success.

My emacs is compiled with XPM support.

Any ideas what did I do wrong?

Thanks:
        Péter