MGCP call farwrding problem

connection from phone A to B is fine(when the asterisk is in between them).
i am pressing the FLASH button and getting again a dial tone in A , and music on B.
then i am dialing to C which is ringing .
when picking up C the transfer fails.
in the trace i can see that the last MDCX fails:

o=root 2374 2374 IN ipv4 \r\n

and of course my problem is because the asterisk sets the ip to