Can't create 2 HE.net ipv6 tunnel

[kingwilliam]

my pfsense 2.1 box with 4 network port,

1st + 2nd = lagg LAN
3rd is WAN-A
4th is WAN-B

both WAN are create HE.net ipv6 tunnel with different ipv6 tunnel
both server ip is 216.218.221.6

but, only 1 tunnel work, can't keep both tunnel online.
if WAN-A active, WAN-B will offline
if WAN-B active, WAN-A will offline

anyone can help me?