[Chimera-users] Non-alphanumeric character in keyword

[MPI]

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