"Microsoft Active Directory - Exchange Extension" – Errors

[Big10uk]

The background
============

I have two domains mydomain.co.uk & child.mydomain.co.uk, I am in the middle of implementing exchange 2003 in our mixed mode domain.

Mydomain.co.uk (AD Mixed Domain)
DC01.mydomain.co.uk (GC)
Exchange 5.5 Srv

Child.mydomain.co.uk (AD Native Domain)
DC02.child.mydomin.co.uk (GC)

I have installed the ADC connector on both my domain controllers (mydomain.co.uk) and my child domain (child.mydomain.co.uk).

I have created two two-way agreements for my objects in exchange to sync with AD:


Connection agreement for mydomain.co.uk
=================================

Objects from Exch 5.5
------------------------------
Mailboxes
Custom Recipients

Objects from AD
-----------------------
Users
Contacts


Connection agreement for child.mydomain.co.uk
=================================

Objects from Exch 5.5
------------------------------
Distribution Lists

Objects from AD
-----------------------
Groups


The problem
==========

When I administer my child domain (child.mydomain.co.uk)from mydomain (mydomain.co.uk) and look at my security groups or any other object I get the following error:
Microsoft Active Directory – Exchange Extensions
------------------------------------------------------------------
The operation failed.
ID no: 80004005
Microsoft Active Directory – Exchange Extensions.

I have look on TechNet and can’t really find any solution.

Can anyone please help me.

Thanks

James