SQL Query to select users who have NOT voted

[Luke Brown256]

Hi i am trying to write an SQL query that would select all users from a specific usergroup who have NOT voted in a specific poll:

SELECT vb3_user.* 
FROM vb3_user LEFT JOIN vb3_pollvote ON vb3_user.userid=vb3_pollvote.userid 
WHERE vb3_pollvote.userid IS NULL
AND vb3_pollvote.pollid = 240 
AND vb3_user.usergroupid =26

that is what i have got so far, but it returns blank results, can anyone assist with this?

Luke Brown