[Chimera-users] Non-alphanumeric character in keyword

Dear users, In Chimera, I tried to run a vina docking in command line like vina docking receptor #0 ligand #1 output mytest search_center 10,20,30 There is an error: Non-alphanumeric character in keyword 'search_center' I have tried tweaking the keyword 'search_center' in different ways but the error won't go. Dose anyone know how to fix it ? or is this format correct ? Many thanks, Dwey