Trying to purchase September airfare

[#1Disfann]

I have been waiting and watching for September 2005 airfare to be posted. When I do a search (several sites) I find the cheapest so far is Spirit but when I go to Spirit's site (and when I called them) they say they are not selling for September 1-8 yet. So why do I find the dates, times, flight numbers, type of plane, etc... on the other sites (travelocity, sidestep, onetravel, etc). Anyone have a clue?