I am having trouble getting a hangup hook to execute after an api originate.

bgapi expand originate {api_hangup_hook=confhanguphook.lua,session_in_hangup_hook=true}sofia/internal/2001@${switchvox} &conference(25bce61d-fb32-44d7-8d99-7ceafc599f22@sla)

I get into the conference just fine but the script does not execute when I hang up.  Any Idea's of what I am doing wrong?

Bob