ThickBox Being Overlapped

http://direxit.com/newcontactform.html

I have a client’s website and I am trying to integrate a ThickBox Lightbox to pop up and display a contact form. I have been able to get the Lightbox to appear, but no matter what technique I use the menu elements seem to overlap it.

I’ve read able changing the z-index to a higher value, I’ve tried a plugin …

Has anyone got any ideas?

If you go to the link above you should click on the ‘Apply Now Link’ to see how the lightbox is not working