Further to what Athanasius posted: If you really want to use a lexical (i.e., my) variable, try:

c:\@Work\Perl>perl -wMstrict -le
"my $a  = 25;
 my $ra = \$a;
 ;;
 print $ra;
 print $$ra;
"
SCALAR(0x432814)
25
[download]

Please see perlref, perlreftut.