After placing the BB_DVDATASETELEMENTS = 1 configuration variable into the .UCF file, the new levels are still missing.
There is a configuration variable that controls where AECOsim Building Designer looks for levels:
Typically it is configured to look at all of the files in the dgnlib folder that follow this naming format:
Double-check that variable to make sure that it is set to pickup your dgnlib file. You can edit the variable to include your specific file name.