Help... DFP Update not working

I have been trying this now for a good four or five hours, and I can't get it to work. I used to be able to do it fine in DFP1, but I am using version 2 now and the online videos don't match version 2, even though I have managed to figure out the differences... or at least I think I have.

I have entered content into the db via the insert, the image has uploaded and is displaying great from the insert page.

It is also working great from the update page if I want to update the image... however, the problem is that if I just want to update text and NOT the image, the data that is already in the update field is not being passed over as default and deleting the info for the image that is already there.

In the DFP panel, I have set...
File field: imagenameFile
Default file: imagename (from the Update Form info which is the hidden field)
Upload: images/stock/
File name: [Filename]

In the Update Record behaviour from the server behaviours panel I have set...
Select imagename in list
Click lightning bolt
Choose Server File Name from Upload File

The code for the page is attached.

Thanks.