There's limited info to go on. The environment, new report, just this report, version used, accessing through the browser/client etc etc.
To me it seems to be a licensing issue. In the QMC System-licenses-server CAL's, ensure to check "allow dynamic CAL's" and/or "Allow License Lease", verify number assigned to number in the licenses available.
If it's a client, set the QV Server AP in the user preferences to be assigned a license to the user when they open open the access point under tools.
