[PyMOL] how to alter the "reps"

Hi all,

I have a question about alter command on "reps" variable. I find reps is
zero when object being set with "hide everything". I try to modify one
atom's reps to be zero by using the following alter command:
   alter (resi 84 and name CE1), reps=0
It seems the reps do changed to 0, but that atom is not being hidden. My
question is: do we need to refresh the representation after altering one
atom's reps? if yes, how to do that?

Thanks in advance!

Junjun