I'm trying to run CST on an HPC cluster (RHE9) in batch mode with the time domain solver and a parameter sweep with the following command: 

xvfb-run cst_design_environment -m -p -withgpu=2

This doesn't work. Using the '-r' option works. Adding option '-as' with '-p' just runs the time domain solver without parameterizing. What is the correct syntax for what I'm trying to do?