The way this should be setup is to have the upload server behavior on the page first. You should not have any image file restrictions in place in this server behavior. This should allow you to get the pdf uploaded.
Next you will add in your insert or update server behavior. You can set the trigger of this server behavior to all uploads successful so that it will not insert or update if the uploads do not occur. In this server behavior for the ProductFloorPlan column you will want to bind the server file name from the upload bindings.
When setup like this you should be able to fill in the form, have the file upload, then have the insert or update occur with the server file name. Please post back and let me know how you have things setup compared to this overview. If you have any part of this that is setup differently let me know. Also if you continue to have problems with this please post back with the insert and update pages and the table structure in a sql file. I can use these files to do some testing to help determine what may be wrong.