I'm pretty sure I can fix your form submission, must be some validations gone wrong (or some JavaScript namespaces conflict)... I have worked with LightWindow-like controls for a few years now, and I'm a JavaScript grand-master for about seven, so... I think your challenge won't be to much of a hassle.
I see, though, that on your web page you have linked the form directly into the page (that is, it's not displayed in the LightWindow anymore). Can you provide a test / sample page, with the original issue?