[Chimera-users] Depiction of backbone CA atoms as spheres

I’m trying to depict selected backbone atoms as spheres with a smaller vdw radius. Residue side chains should not been shown. I checked the list and found an option that appears to do the job, e.g sel :77-80, 91-94 repr bs @ca vdwdefine +1.0 @ca But this didn’t work for me. Grateful for any suggestions Thanks in advance George