As well as the DOS line-ending issue that others have mentioned, it might also be the shebang (#!/usr/bin/perl) either being missing or not having the correct path to perl (I am assuming the server is some Unix like OS), you don't need this on windows as IIS uses the extension of the script to know which interpreter to use, but it is necessary on Unix to run a script as an executable. It could also be due to the permissions of the script file - it needs to be executable and readable by the user that the web server process runs as.

/J\