Quote from piripiago on October 30, 2013, 4:01 am

I've found prop_portal to be very finicky when I am using more than one with the same color and ID number in a map. A way to force it to obey though is to use the "NewLocation" command. Use the same trigger and delay that you are using for the SetActivatedState:

trigger; portal_name; NewLocation; x y z pitch yaw roll; delay

Place a point entity at the center of where you want the portal to appear and select it to see the x y z coordinates at the bottom of the window just to the left of the display for the zoom and snap scales.