Thanks for getting this page to me. The updated insert server behavior has been edited correctly and you have setup the insert parameters without error. The problem is that this code is never being executed. You have the action of the form still going to the product insert page. You should either leave it blank or set it to this Markers insert page.
I did a test of your page with a copy of my products table and can confirm that the userID is making it's way into the table.