Can't access OWA by Exchange 2013 in a mixed environment with Exchange 2007

Hi ALL

I'm with the follows problem: I can't open any mailbox from Exchange 2013 and from Exchange 2007 accessing by Exchange 2013 - OWA. I receive the message: 

something went wrong

Sorry, we can't get that information right now. Please try again later. If the problem continues, contact your helpdesk

Details:

X-ClientId: UD9E - SNEW - J0GA - RUWHA0MG

X-FEServer: WPFEX01

Date: 24/11/2015 19:03:15

https://blablabla.domain.com/owa/auth/errorFE.aspx?httpCode=500

When I try to open a Mailbox from Exchange 2013 accessing by OWA (Exchange 2007), I receive the following message:

403 - Forbidden: Access is denied.

You do not have permission to view this directory or page using the credentials that you supplied.

Obs:.Accessing mailbox from Exchange 2007 by the OWA from the Exchange 2007 no problem.

Obs2:. the ECP is working.

Anybody has a suggestion?

Thank you

Martins