I created a dashboard with prompt and analysis. It works great in DEV and PROD but the prompt doesn't populate the values in QA. The prompt contains only one column C1
One thing you should know is QA doesn't have enough data but it has atleast 2 values for C1.
1) Set LogLevel to '5' for your account.
2) Purge all cache (BIServer, BIPresentationServer).
3) Open your dashboard.
4) Look at session log (Administration - Manage sessions - find your session by logical SQL query)
Perhaps the physical query will be helpful for you.
Copy the query for the prompt from Dev environment query log and run that query against the QA database. Now check whether you are getting those 2 values or not.
If yes, then you have to ask the Administrator of QA environment to purge cache.