Hi Vikram,
First:
You mentioned that you are using SFW 5.1 but did not mention if you are running SP1 for SFW 5.1. If not you should be running it because it contains many fixes for the Windows Failover Cluster. You can get SFW 5.1 SP1 from the fileconnect website.
In addition to SP1 you will need to run a public patch that allows Dynamic Quorums to work correctly with Windows 2008 R2. This patch can be found at:
https://vias.symantec.com/labs/vpcs/vpcs/patchinfo/3090
Next:
Stop the Cluster service on both nodes. Make sure that you can import and deport the Clustered Dynamic Disk group and move it from node to node without any issues.
You did not mention that the diskgroups that you created were Clusterd diskgroups. With the diskgroup import check in VEA to see if the diskgroup show "(Clustered)" when selcted. If the didk group shows a "(Secondary)" then you will need to deport the diskgroup, then while importing it in VEA select the check box option to make clustered disk group.
If everything is working fine at this point, reenable the Cluster service and start it on both nodes.
In Cluster Administrator, display the properites of the Veritas Dynamic Diskgroup resource and go to the parameters tab. This tab has an attribute for the diskgroup name. Ensure that this diskgroup name matches the diskgroup name in VEA (case does matter.)
From there if everything still looks fine but failover is not working as expected, you might want to open a case with Symantec Technical Support. We will need a set of VxExplorer logs to determine what is going on. VxExplorer logs will gather logs related to SFW and the OS including the cluster.log for Windows Failover Cluster.
Thanks,
Wally