You will want the delete file behavior to run first... what about setting the trigger to "delete file successful". That should be an option. I think the other you need to do now that I think about is make sure you have enclosed the delete photo button within a form. You will also want to put a hidden field within the form where you have the value of the row's id. That way when you are updating the row, you can specify the correct id.
Let me know what you find out... after that, if there are still problems; if you can, post the code here and I will take a look at it.