I have spent this evening searching and researching on this, and other forums however I can't seem to get this working.

http://www.tekkerstraining.com/book

I am trying to link to this form from various other areas on the website so the 'Courses' field at the top, is pre-populated.

Ie. If you click 'Book Now' from the Excel page, then it will select the Excel course in the drop down box automatically.

I've enabled custom ID's and disabled AJAX. I'm not sure if I'm getting confused here – but I've tried linking by adding a ?course=adobe-indesign to the end of the URL and it's still not working.

Any advice greatly appreciated!