Can't use string ("%s") as %s ref while "strict refs" in use
  (F) Only hard references are allowed by "strict refs".  Symbolic references are disallowed.  See perlref.

##</code><code>##

$im->filledRectangle($X1,$Y1-20,$X2,$Y2,\$genecolor);

##</code><code>##

$im->filledRectangle($X1,$Y1-20,$X2,$Y2,$genecolor);