NCM Query

I am trying to get the total devices count on dashboard,  which are currently not backedup using below query.  

but still getting the wrong count, can you  @christopher.t.jones123 please suggest how i can get the notbackedup devices count.

SELECT
COUNT (CASE LoginStatus WHEN '' THEN 1 else NULL end) AS [Count], 'Not Backed Up' as [Status]
FROM NCM.Nodes