Hi Shunming, There should not be any spaces after the "," in your command. Something like the following should be fine: sym #1 group h,11.75,101.32 Although "normal English" requires spaces after commas, commands are different! I hope this helps, Elaine ----- Elaine C. Meng, Ph.D. UCSF Computer Graphics Lab (Chimera team) and Babbitt Lab Department of Pharmaceutical Chemistry University of California, San Francisco On Apr 22, 2011, at 8:38 AM, Fang, Shunming (NIH/NIDDK) [C] wrote:

Hello, There, I tried several time to use the commend sym #1(or 2,3..), group h, 11.75, 101.32 to my em map, it always show errors saying unknown keyword 11.75, 101.32? Please help me, Thanks Shunming