problem executing linux command in perl

[Rahul Garg]

Hi,

I am transfering xyz.txt file from windows98 to linux server manually. 
$r_file = "xyz.txt" ;
then in perl script i am executing  `chmod 0777 $r_file` ;
# $r_file is in the same directory as is perl script
but the line is not executing 
i have tried system command too.
Any suggestions..
Thanks,
Rahul,