Why won't the hiddenfield data insert itself into the table

I use DataAssist all the time and usually have no problems but on this occasion it's beating me. Admittedly I'm customising the page a bit but some of it works and some doesn't. I know I'm missing the obvious but I just can't see it.

So, this is what it's supposed to do.

From a previous page the INSERT RECORD page is displayed but pulling an existing record using a recordset and populating that with a URL parameter from the previous page. I've tested this and all the correct information is displayed. Some fields on the insert form are pre-populated using hidden fields (getting their values from the recordset) and then these hidden fields are used to INSERT into a new record together with new information.

That all works fine apart from one hidden field that will just not insert into the new record. The offending hidden field is "origEmailID". I have attached the page and the database schema in case it's something to do with that.

What baffles me is that other hidden fields insert fine, with no bother.

So the question is; why won't the "origEmailID" insert itself into the table.

If anyone can help I'd be most grateful, many thanks.