Since this is a CGI process responding to a submitted form from a web browser, I believe the browswer is expecting to get some HTML data back, and it would get this when your script prints some amount of text to its STDOUT that qualifies as a valid HTML "page". But you are not printing anything out to STDOUT, so nothing is being returned to the browser.

Look at the man page for the CGI module, for a simple example of how to output a minimal HTML "page" to keep the browser happy.