Issue with universe created on top of a web service

Dear Gurus, I have created a universe based on a web service in IDT (4.1). I added some SQL code in the field ‘Value’ to return the desired results:

However, when trying to view the result, I get an error message:

Any idea what could be wrong? I search through the internet but there is little (if none) information on how to build such universes 😔

Thanks for the help. Sébastien