you should read the manual regarding callbacks. you should not have created a callbk dispo, but you should have activated agent only callbacks on each user record and allowed callbacks in the campaign. agents should not be able to choose calback hold, that's an internal function used to hold callbacks until their time has come.
if leads that are dispo'd as "SALE" are being called again, and you do not have "SALE" as a dialable status on the campaign, turn off lead recycling. reset the list instead of using lead recycling. and read some more posts on the topic, they may be interesting.
Welcome to the party!
(good job posting your specs, but I do not think you are running SuSE 11.2 ... just sayin' ...)