MS SQL - Using SUM and CASE to get counts

Hello,

I am using SUM (CASE... to get counts.   The query does not seem to return the correct values.  When I do just  Select COUNT(*) from Table Where (Single criteria), it returns a different value.

What am I doing wrong here?

Thanks

SELECT 
 SUM(CASE WHEN (DMStype = 'ADP' And PollStatus = 'Complete') then 1 else 0 end) AS ADPcomp,
 SUM(CASE WHEN (DMStype = 'ADP') then 1 else 0 end) AS ADPtot,
 SUM(CASE WHEN (DMStype IN ('RR','RRC') And PollStatus = 'Complete') then 1 else 0 end) AS RRComp,
 SUM(CASE WHEN (DMStype IN ('RR','RRC')) then 1 else 0 end) AS RRtot
From MyTable
Where DMStype IN ('ADP','RR','RRC') And DealerStatus IN ('Prod','IPRO','Stage')

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