Cat Messenger Display not clearing trip totals

I have two Cat Messenger Display's (P/N 302-0417) on our boat for the C12 engines (S/N 9HP) and I am unable to reset the trip data.  I go to the reset menu and it says it has reset the data but it never clears it.  The trip totals and life time totals are always the same.  Any idea why they won't reset?