Can you see it being loaded on the front end though? Also is the jquery file on the front end being included before your file. The requirements class does do some reorganization so what you have the in PHP may not always reflect whats actually included on the front end. If all the files are being included you might want to check the contents actually exist and otherwise do google search http://old.nabble.com/jQuery,-$-is-Not-Defined-Errors-td18801392s27240.html.
pinging off this topic. I have a website that is reporting an error in the forum.js file that jquery is not defined. In the generated page source forum.js is being loaded prior to jquery.js which is (of-course) an issue.
All the files are being loaded via the Requirements class.
Is there any way to force the load order? Or another simple way to load the scripts in the correct order (other than brute-force via lines in the header template)?