Kerberos 4 Ticket Granting Ticket

[ms419@freezone.co.uk]

I have installed zephyr, which uses kerberos 4 rather than 5. My 
installation of the debian packaged, MIT kerberos distribution is 
working without problem. I enabled full kerberos 4 support. Following 
instructions, I added the principle zephyr/wum.lat at LAT to my kerberos 
database, then extracted it to a kerberos 4 srvtab. "kinit -4" 
succeeds, with the following line in "auth.log":

Dec 23 22:34:10 wum krb5kdc[6886]: PROCESS_V4:Initial ticket request 
Host: 192.168.179.73 User: "john" ""

"klist" lists the following kerberos 4 ticket:

Kerberos 4 ticket cache: /tmp/tkt1000
Principal: john at LAT

   Issued              Expires             Principal
12/23/03 22:34:10  12/24/03 08:34:10  krbtgt.LAT at LAT

"zwrite testuser", however, complains:

zwrite: Don't have Kerberos ticket-granting ticket (get_ad_tkt) while 
sending notice to testuser

It produces the following lines in "auth.log":

Dec 23 22:43:44 wum krb5kdc[6886]: PROCESS_V4:APPL Request john. at LAT on 
192.168.179.73 for krbtgt.wum.lat
Dec 23 22:43:44 wum krb5kdc[6886]: PROCESS_V4:UNKNOWN "krbtgt" "wum.lat"

Anyone know what I've done wrong?

Thanks,

Jack