problem with Illidan morphing - please help

I gave Illidan the Locust Swarm Hero ability. When I use it in the game he morphs into Demon form as he does with his metamorphosis ability. How do I prevent him from morphing when using Locust Swarm?

I appreciate any help at all. Thanks.

Note: I'm using the old Illidan model from roc (without the wings or horns).

the problem is the order-string...
maybe metamorph has got the same string as locustswarm
just look what the string is and tell us...

Text - Order String - Activate : None
Text - Order String - Deactivate : None
Text - Order String - Turn Off : None
Text - Order String - Use/Turn Off : Locustswarm

I've tried changing the top three to metamorphosis but it didn't work. I'm not really sure what they do.

Edit: Maybe I'll have to use a trigger to change him back...