XCP-NG cannot mount iSCSI from Freenas

First time on the forum,

I have just recently started a cleaning of my lab env, after detach of iSCSI SR from hosts i cannot plug them back again.
from XCP-NG Center:
I can scan Target Host, i see the IQN, i see LUN…
System inform me that "An existing LVM over iSCSI SR was found…
giving me two options: Reattach or format
Reattach giving error “Plugin PBD, The storage repository is not available”
Any ideas?