Reading maps produced by r.mapcalc

Hi there!

I'm working on the development of a 2D overland flow programme. (Fully
dynamic, solved by a 2 step predictor-corrector MacCormack explicit scheme).
The main problem I am facing is that I am unable to read those maps I am genet
ing through r.mapcalc. Inside my GRASS4.1 programme I have some "awk" sub-
routines calling for r.mapcalc. The maps so produced can be displayed etc BUT I
cannot use them as input maps.
Commands like
     G_legal_filename,
     G_find_file,
     G_open_old etc
give always fatal errors.
However, if I read the maps interactively, everything is OK.

What am I doing wrong??

Thanking you,

Roger Chenevey
Dept. of Hydarulic Engineering
Royal Institute of Technology
S-100 40 Stockholm