[sync] Sync fails with Nokia 6280

[Simo Kivimäki]

I cannot sync Horde's calendar with Nokia 6280 using SyncML. I'm using
CVS snapshot of Horde, Framework and Kronolith from 2007-09-18. Syncing
works with Nokia E65 so I suppose that the installation is OK. I'm using
Ubuntu Linux with PHP 5.2.1 and Apache 2.2.3.

After trying to sync, the phone says "Data transfer not possible" and
then "Synchronization info, Calendar: Incomplete".

No php errors showed up in the php error log.

/tmp/sync/syncml_log.txt (little bit censored):

DEBUG:  Backend of class SyncML_Backend_Horde created
DEBUG:  New session created: 8cca688c26165152b4e1966eb9b1c79d
DEBUG:  checking auth for user=kivimaki
DEBUG:  authorized=1 version=1 msgid=1 source=IMEI:3539490xxxxxxxx
target=http://xxxx.fi:xxx/horde/rpc.php user=kivimaki charset=UTF-8 wbxml=1
DEBUG:  SyncML: No info about previous syncs found for device
IMEI:3539490xxxxxxxx and database calendar
DEBUG:  Create new sync for calendar; synctype=201
DEBUG:  HandleFinal for state=0
DEBUG:  Received Final from client.
DEBUG:  Sending Final to client.
DEBUG:  SyncML: return message completed
DEBUG:  Finished at 2007-09-19 12:00:35. Packet logged in
/tmp/sync/syncml_server_10.wbxml

I suppose that after that the phone should send next SyncML message but
it doesn't. Any idea what is wrong and how it could be fixed?