How to select multiple values and then lock a listbox on trigger

[#1]

Hi

I am trying to set up a trigger on an ActivateSheet event to lock a listbox that is based on an expression. I am able to do this on a Listbox that is based on a regular field, but not on Listbox based on an expression.

Thanks in advance for your help.

[Anonymous]

Do you any sample app that you can share