Bridge mode between Aruba controller and Aruba Access point <Not work!!>

Hi all,

I depoly Sophos in bridge mode

Design is :: Aruba Access point (172.16.99.68,69,72) <-------> [Core]<------->  [Sophos] <-----> [Switch]  <----> Aruba controller (10.0.233.79)

ISSUE is

Access Point cannot initial GRE tunnel to controller. I try to config below 

-          Bypass gre by create  policy : any any service GRE allow

-          Bypass IPS by stop service IPS

But It not work.

Please Advice to me.

Thank you

Anupong T. (Jay)