NEED TO ENABLE BULK USERS on LYNC 2010 WITH POWERSHELL using SAMACCOUNTNAME

Currently I am using following command;

Import-Csv C:\Scripts\Users.csv | ForEach-Object{$varUserId=$_.userid; Enable-CsUser -Identity $varUserid -RegistrarPool gn-a-if-lync01.iyogi.net -SipAddressType samaccountname -sipdomain iyogi.net}

WHENEVER I RUN THIS COMMAND I GET FOLLOWING ERROR, MAY BE SOMETHING IS WRONG HERE:

Enable-CsUser : Management object not found for identity "waseem.raza".
At C:\Scripts\lyncuser.ps1:1 char:85
+ Import-Csv C:\Scripts\Users.csv | ForEach-Object{$varUserId=$_.userid; Enable
-CsUser <<<<  -Identity $varUserid -RegistrarPool gn-a-if-lync01.iyogi.net -Sip
AddressType samaccountname -sipdomain iyogi.net}
    + CategoryInfo          : NotSpecified: (:) [Enable-CsUser], ManagementExc
   eption
    + FullyQualifiedErrorId : Microsoft.Rtc.Management.AD.ManagementException,
   Microsoft.Rtc.Management.AD.Cmdlets.EnableOcsUserCmdlet

Any help is appreciated :)

Thanks,

RIWAA

RIWA