If ever you get a message you don't understand like this, run, do not walk, to a command prompt and type:

perldoc perldiag
[download]

Then hit "/", and type in part of the error text, then "n" until you hit the right match if you are not brought directly to the error.

In this case you will find out that you are probably calling the script with perl script.pl when you need to make it executable and call it with ./script.pl.