I don't know if anyone else has spotted this (there are no forum posts).
When using Gtranslate with 'OnFly (JQuery)' you can choose to display Urdu as a language in both the menu and as a flag. However, when you choose it from the drop down list or click the flag, nothing happens!
If you change the translation method to Google Default, Urdu is not displayed as an option in the list - no matter how you choose to display it in the 'languages' bit.
I've checked the Google Translate site to see if Urdu is a language they actually do, and it appears to be!