Yellow Pages problem

[tjcm at stl.stc.co.uk]

We are encountering problems propogating our mail.aliases YP map from our
master server to our slave servers. When the master server tries to push
the mail.aliases map it receives an error status from the slave servers:

> Status received from ypxfr on brown:
> 	Failed - no local order number in map - use -f flag to ypxfr

I believe that I've located what the problem is but have been unable to
come with a solution so far.

According to ypfiles(5) every YP map should have 2 special key-value pairs
YP_LAST_MODIFIED and YP_MASTER_NAME. (These are used by the transfer agent
ypxfr to decide whether a map on a slave server is less recent than the
map on the master server)

On our YP master the YP map 'mail.aliases' does NOT contain these two
values.

# /usr/etc/yp/makedbm -u mail.aliases | head -4
isad-steering-request  dww
viclib-request  dww
bsd-ideas  root
fivegsw  fivegsw at pine

All the other maps I've looked at seem to be configured OK.

# /usr/etc/yp/makedbm -u ethers.byname | head -4
YP_LAST_MODIFIED 0628952682
YP_MASTER_NAME siris
yellow 8:0:20:1:12:67  yellow
wattle 8:0:20:1:b9:8b   wattle

The Makefile in /var/yp uses the program makedbm to construct most of the
YP maps but uses the program /usr/etc/yp/mkalias to build the mail.aliases
map.  This program does not appear to be documented. (not on 4.0.1)

Has anyone else come across this problem or can anyone offer a solution ?!

Can someone confirm that the mail.aliases map contains these two keys on
their system. [/usr/etc/yp/makedbm -u mail.aliases]