serial error with zone transfers

[Michael Long]

We run a pretty tight ship, but we also server as secondary for other
zones out there...and they always no doubt call us to ask why their
zones won't transfer properly to us.  When we look in our logs, all we
get is a message indicating that there is an error with the serial.
When we look at the zone file on the other server, the serial number
looks fine.  Can anyone give me some hints?  We run 8.2.2P5