Setting up a Designate in P051125

I have set up a designate for Employee Self Service to allow another employee to approve time for a manager.  I have set the employee up, the approver and run the relationship build.  However, when the designate logs into the P051125 and selects the Manager Review and Approval the Address book number can't be changed, which is what the documentation states to do.  I have looked in the processing options and it isn't something that I see.  Is there a set up step I have missed for this?