Variables for Hana database

I am having trouble with a report that allows users to edit variables. The report uses HANA,

Everything works fine in Desktop. But it fails in the service. The error message is not very helpful. It just says "Couldn't retreive the data for this visual. Please try again later."

The report is exceedling simple. It's just a grid with a single column. I confirmed that the gateway is up-to-date.