Your script works for me. What error do get in $! ?
can you try adding debug statements like:

my $cwd = `pwd`;
print ("$cwd\n");
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As a side note, you can pass a full path to an open statement. You don't need to be in the same directory as the file to open it and get a valid filehandle.

You've probably truncated your script and you say that your die statement does print, so this might not be applicable, but you should see perlfaq 8.34. A script can't change the parent shell's directory.