Host based Migration using Open Migrator / LM, Unable to attach the volume

Hi Techies,

I need to do a migration from CX4 to new VMAX

Operating system : Windows Server 2008 Enterprise x64 Release 2, SP1.

The Disk has 3 volumes and this is a clustered disk, also the clustered server is not being used temporarily.
its not advised to take the disk from cluster, because later the cluster will be used.

When i tried to attach the volume to open migrator other local disk i was able to do it, however failing to attach this clustered disk.
Please suggest!!!

Cheers,
Paul