iRest calls returning 400 - script did not successfully complete

I'm having issues to call a CLI script using Rest. I'm doing a POST to https:///mgmt/tm/cli/script and all the time the only thing that I get is "Script did not successfully complete". If I try to run the same command using tmsh it works fine so I know that my script isn't failing.

Does anyone know anything else that could lead me to that is causing this problem ? I couldn't find anything in the rest logs...