The error you are getting isn't a Perl error. It looks like a shell error - and 'qsh' is indeed an IBM shell.

Now, the she bang line is a Unix trick (the kernel looks at the first two bytes of the file to see what kind of excutable it is - in the case of '#!' it isn't an executable, but data for the program that follows). But I don't think Unices are the only OSses that can run on the AS/400.

So, what OS are you running, and how are you calling the script?