Bartender RDD from BAQ

I’m trying to use an RDD connected to a BAQ for a Bartender label. When I try to print or print preview, I get an error in the System Console:

Program Ice.Services.Lib.RunTask raised an unexpected exception with the following message: RunTask: Value cannot be null.
Parameter name: key

Has anyone printed a Bartender label using an RDD from a BAQ? Any idea what is missing to cause this error?