What's wrong with this query

SELECT Tickets.TicketID, Tickets.Title, Tickets.Description, Tickets.Software, Tickets.Date, Systems.OS, Rating.DateVoted, Rating.RatingID
FROM Rating INNER JOIN
Tickets ON Rating.TicketID = Tickets.TicketID INNER JOIN
Systems ON Tickets.SystemID = Systems.SystemID
WHERE (Systems.OS = @osid) AND (Rating.DateVoted >= @date)
ORDER BY COUNT(Rating.RatingID)

It's meant to list tickets which match a type of OS and ranks them based on all the amount of rows in the rating table, whose dates are above a speicifed date..

 

In your first select you only grabbed one table before the first join.