Redhat Cluster Fencing failed

Hello;

I have 2 node Redhat Cluster (RHEL4 U4 and Cluster Suite) I'm using mc_data fiber channel switch for fencing

when I want to fence manually using
fence_mcdata -a x.x.x. -l xxx -p xxxx -n 5 -o disable

following messages appears

fencing node "test1"
agent "fence_mcdata" reports: failed: unexpected port state

How can I resolve this issue ?

Thanks