CR Session Management - Open Gift Session can't be Balanced

Can anyone tell me what would cause an open gift session with the expected and actual totals balancing to not display the Balance button to balance the session?  I have looked at everything I can think of with the session and gifts, and I don’t see anything incorrect.  It is a session with both cash and check tender types, and gift and pledge payments combined, but I think that can be done.

We recently lost our seasoned gift processor, so I am trying to help the new users work through some of these issues.

Thanks,

Janelle