modifying management Scope

Hello Cool People, 

I'm trying to modify an existing management scope  to change the recipientrestriction fillter to a new mailbox. 

Set-ManagementScope -Name "My Custom Scope" -RecipientRestrictionFilter {Name -eq "New Mailbox"}

But as soon as I hit enter, it prompts me with this:

cmdlets Set-ManagementScope at command pipeline position 1
Supply values for the following parameters:
Idenity:

I have done this a couple of times before and its just now where it prompts for this. What Information does the "Identity"needs