Hi mrahul,
Yes I managed to get to the bottom of this after logging a support call.
This issue was I was running the cmdlet on my local machine after using open-smconnection to the SnapCenter server.
NetApp have confirmed that the cmdlets are not supported to be run from anywhere but where SnapCenter server is installed. It's rather disappointing as it makes remote administration and automation difficult and these are some of the things that PowerShell used for. With the SnapCenter cmdlets you have to either wrap everything in invoke-command or run the script on the SnapCenter server directly.
A request was put on by the NetApp support person (ID 116845) to request the cmdlets are tested for remote usage and if possible provide support for remote usage.