Robert,
I had the same issue
Substitution/replacement variables need to be quoted and they must come before the EXEC= in the command line.
For example:
queryreporter.exe userid=.../..@... "&RD=21/10/2003" exec=report.rep html=report.html quit
Apparently the command line params after the EXEC are not processed until after the query is executed.
Topic: vars on the command line --marc