Ringgroup Memoryhunt doesn't work correctly

Good Morning,

i have here some suspect behavior by using memoryhunt in ringgroups. but first some details from the used stuff:

running:
asterisk 1.6.2.24
freepbx FOP 2.10.1.2
freepbx Framework 2.10.1.2
Ring Groups 2.10.0.6
mISDN for the Junnghanns Quadbri

sccp v2 with some Cisco 7960 and 7961

The Problem is, when im using memoryhunt or memoryhunt-prim in my ringgroups every new extension in the ring group gives a missed call for the still ringing extensions. i ve checked the logs and saw that there is a hangup before starting ringing the next extension and the last one.

dialparties.agi: Methodology of ring is ‘memoryhunt’
– SEPXXXXXXXXXXX1: Channel SCCP/105-09a65a90, capabilities: DEVICE 0x10c (ulaw|alaw|g729)(268) PREFERRED 0x8 (alaw)(8) USED alaw(8)
– SEPXXXXXXXXXXX1: Asterisk request to call SCCP/105-09a65a90
– SCCP: Channel ‘0x099f6758’ freed by schedule.
– SCCP: Channel ‘0xb5700fc0’ freed by schedule.
– SCCP: Asterisk request to hangup channel SCCP/105-09a65a90
– SCCP: Request to schedule delete for channel ‘161897104’ in 10 seconds
– SEPXXXXXXXXXXX1: Channel SCCP/105-09b4eb40, capabilities: DEVICE 0x10c (ulaw|alaw|g729)(268) PREFERRED 0x8 (alaw)(8) USED alaw(8)
– SEPXXXXXXXXXXX1: Asterisk request to call SCCP/105-09b4eb40
– SEPXXXXXXXXXXX2: Channel SCCP/104-09b53c48, capabilities: DEVICE 0x10c (ulaw|alaw|g729)(268) PREFERRED 0x8 (alaw)(8) USED alaw(8)

i tried to use the dailing option c for flagging the call as ansered somewhere else without success.

Do you have any ideas?

Thanks alot
Karl