smpp dlr problem

Using kannel cvs (1 month ago) smpp internal storage
I send one sms with dlrmask=31:
2003-05-06 15:27:00 [5] DEBUG:   message_id: "2976249"
2003-05-06 15:27:00 [5] DEBUG: SMPP PDU dump ends.
2003-05-06 15:27:00 [5] DEBUG: Adding DLR
smsc=SMPP:xxx.xxx.xxx.xxx:2775/2775:futuress:VMA, ts=2976249, src=Visco,
dst=+39347zzzzzzz, mask=31, boxc=smsboxA
2003-05-06 15:27:00 [5] DEBUG: Looking for DLR
smsc=SMPP:xxx.xxx.xxx.xxx:2775/2775:futuress:VMA, ts=2976249,
dst=+39347zzzzzzz, type=12
2003-05-06 15:27:00 [5] DEBUG: created DLR message for URL
<http://yyy.yyy.yyy.yyy/mydlr.asp?valore=%d&valoresmsc=%A&uniqueid=77500>


I receive it, but afer few minutes I got the delivery report:

2003-05-06 15:47:18 [6] DEBUG:
SMPP[SMPP:xxx.xxx.xxx.xxx:2775/2775:futuress:VMA] handle_pdu, got DLR
2003-05-06 15:47:18 [6] DEBUG: Looking for DLR
smsc=SMPP:xxx.xxx.xxx.xxx:2775/2775:futuress:VMA, ts=0002976249, dst=Visco,
type=1
2003-05-06 15:47:18 [6] DEBUG: DLR not found!
2003-05-06 15:47:18 [6] ERROR:
SMPP[SMPP:xxx.xxx.xxx.xxx:2775/2775:futuress:VMA]: got DLR but could not
find message or was not interested in it
2003-05-06 15:47:18 [6] DEBUG:
SMPP[SMPP:xxx.xxx.xxx.xxx:2775/2775:futuress:VMA]: Sending PDU:
2003-05-06 15:47:18 [6] DEBUG: SMPP PDU 0x1004c428 dump:
2003-05-06 15:47:18 [6] DEBUG:   type_name: deliver_sm_resp
2003-05-06 15:47:18 [6] DEBUG:   command_id: 2147483653 = 0x80000005
2003-05-06 15:47:18 [6] DEBUG:   command_status: 0 = 0x00000000
2003-05-06 15:47:18 [6] DEBUG:   sequence_number: 1 = 0x00000001
2003-05-06 15:47:18 [6] DEBUG:   message_id: NULL
2003-05-06 15:47:18 [6] DEBUG: SMPP PDU dump ends.

The service was not restarted during this 20 minutes so I don't undesrtand
why
DLR was not found.
Any idea?
Thanks
Andrea