Just for configuration testing, I am creating single 10G FC vLAG from Brocade VDX to Cisco 6509. It is straight forwarded.

BrocadeSW:

interface port-channel 9
switchport
switchport mode trunk
switchport trunk allowed vlan all
no shutdown

Interface TenGigabitEthernet 5/0/48
channel-group 9 mode active type standard
no fabric isl
no fabirc trunk
no shutdown
lacp timeout long

on Cisco 6509

interface port-channel 9
switchport
switchport mode trunk
switchport trunl allowed vlan all

interface TenGigabitEthernet 8/4
channel-group 9 mode active type standard
switchport nonegotiate
no shutdown

Make sure port-channel 9 is up  and line protocol is up

show port-channel 10

Also make sure interface is up and line protocol is up.

show port-channel detail. Sync status should be 1 to show the link is functional.