Weird Airfare Search - Spirit

[#1Disfann]

OK, this is weird! The window for my Sept. 05 trip has just opened up with some (not all) airline carriers. When I use a couple of different search engines I am getting the best price from Spirit. (I fly out of Detroit Metro). When I go to Spirit's website it says no fares are available. So...I called them to ask why and was told they are not selling September yet...just thru August. I told her I was finding Spirit fares on the search engine sites (even flight numbers, times and aircraft types) and she said that could not be and that if I tried to actually book I would not be able to. Anyone know what the problem is??