JQL query "not in ()" dont work as expected

Example:

Steps:
1. Restore the attached data.
2. Login as veenu/pass.
3. Goto advanced view and run a query "project = dashboard and fixVersion not in releasedVersion().

Result:
1. No matching issues.
2. I was expecting all issues in dashboard project having fix version which are not released.

Expected:
1. It should return all issues having fixVersion which is not released.