V1.5 FX Insert problem?

Is it possible to use a rack FX as an an insert on multiple chanels? My goal is to insert a De-Esser in the chain of multiple vocal channels. So far, I am able to assign one, but the moment I assign the next channel the previous channel comes up with an error saying “Invalid Insert”. I’ve attached two pictures, Vox1 and Vox2, Vox2 having the insert successfully, Vox1 showing the error.

here are the pictures

and the other picture

You need to either use one effects slot insert per channel, or route the channels through a group, and put the insert on that.