Hi Craig,
Thank you for your help! My problem turned out to be "HAVING ViewProperty >0", which turned out to a redundant step in my process since the RESULTS table will never conatain a property that has not been viewed. My new query (posted below) is now giving the correct results and totals.
Thanks for pointing me in the right direction!
SELECT ListingID,StreetAddress, City, [State], SUM(ViewProperty) as ViewProperty, SUM(EmailAgent) as EmailAgent, SUM(AgentWebsite) as AgentWebsite, SUM(PDFFlyer) as PDFFlyer, SUM(Directions) as Directions
FROM Results
GROUP BY ListingID,StreetAddress, City, [State]
ORDER BY ViewProperty Desc