Unfortunately I don't know either language. Your response did spark a revelation though, I changed some field names and now it all works correctly with the code provided above. Thanks for that!
I do have an additional issue though. I've been working on this in Abobe Professional 9.4 and I've developed my PDF form that I want my users to fill in but when I open the form in reader the D column no longer calculates. I'm not sure if I had to do a final "publishing" step to make the form operational but if you could point me in the right direction that would be great.