my $fn = join('', 'D:\DATA\Software\MFLOW2\MOD_CL\INSTALL\MOD_CL\INSTALL\RDBMS\c', $template, '.pks');

##</code><code>##

my $fn = "D:/DATA/Software/MFLOW2/MOD_CL/INSTALL/MOD_CL/INSTALL/RDBMS/c$template.­pks";