New-PSDrive returns error :- Object reference not set to an instance of an object.

hi,

I am trying to run sccm powershell cmdlets like 'get-cmsite' etc from Powershell.

I tried following steps:-

1. import sccm module

2. change drive to CMSite

i get error in 2nd step (CMSite does not exist for this user), on further investigating found out that CMSite drive is not mapped for this user (Get-PSProvider - CMSite drive is empty)

I tried to map CMSite drive to its provider by using this command but getting below error:-

New-PSDrive -Name "Dev" -PSProvider "CMSite" -Root "SCCM.domain.com" -Description "SCCM Site"

New-PSDrive returns error :- Object reference not set to an instance of an object.

IF any one can help, that would be great.

thanks.