FTP->Binary

I am trying to get my program to switch to Binary mode. I know the command
is ftp->binary();, however, it does not work. By chance, i got the program
to work only when i have the following lines of code inserted:
$bin=$ftp->binary or die "Can not change the Type to Binary\n";
$bin=$ftp->binary;

If I take out any of those lines it transfers in Ascii mode. Why?

Thanks
Isaac