EV Buttons missing in OWA

Hello,

EV buttons are missing in OWA.

I enabled the log on the CAS server and got the following error message. I really do ont understand how to solve my issue

EVReason: Invalid URI: The format of the URI could not be determined

The customer use  :

2 exchange 2007 server runing on w2k8 platform.(each have cas and mailbox role installed)

One EV 11.0.0 server (runing on w2k8R2)

Many thx for help !