Hi Ray, I just found the solution on an answer you gave to another user on a similar situation. I got it to work now!
In case someone else needs to know here's what happened. The server validation tutorial shows an example where the validations are applied on the confirm page, coming from a checkout page with the form to validate.
In this case, I followed Ray's advice that goes like this and has to do with the order of the functions and what page to be applied to:
"Server Validation, File Upload, and Insert Record server behaviors must all be applied to the same page, in that order, and that page should be the action page of the form."
So, I moved my check unique database value server validations from my landing page to the page that has the form fields I wanted to validate in the suggested order. All worked smoothly.
Maybe is on my particular case, but it worked for me, again I was only checking for two values against the database, nothing else. And I had a file upload as well. All worked perfectly following the order and moving all validations to the page with the form to be validated, also.
Action attribute on the form was set to empty and all validations were set to perform on form submit or button clicked. That's it.
Hope it helps others!