so, you have a Dreamweaver insert behavior that does not insert anything to the images column, followed by the upload server behavior, then the Data Assist insert server behavior to insert the image.
this wont work.
the error is happening on the DW insert behavior, since nothing is being inserted to the image column, it is causing the error.
even if the error where not occurring, it still would not work, because you would have one record for the product info, then another record for the image.
get rid of the DW Insert record behavior, and keep the data assist one.
set the data assist insert record behavior to use the form bindings for the other columns.