I mostly use document.getElementById('boxname').property to referr to objects since I don't have to change the code if I add/remove forms and other objects surrounding the target object.
All you should have to do to your original page would be adding a new hidden textfield and write the dynamic data to both the div and the input using getElementById and then the info would get submitted with the form... strange that it's not working since I've used this method before and it worked fine...
As I said, send me the code and I'll take a look at it, we must have overlooked something...