Anyone using a Stans kit? ??? Have problems? ???

My front tire is perfect. No leaks. The back is a different story. The first week it was losing air real slow. (maybe 5 lbs / 3 days). I was going to go for a quick 1 hour ride after work yesterday, and the floor pump broke and the tire went completely flat. Once you are flat you are SOL pumping it back up unless you hae a compressor. (I don't yet.) Today I went to the LBS and they used the compressor to fill it. I re-mounted it, and checked on it an hour later, and it was allready soft. Pumped it back to 40lbs with the mini-pimp, and an hour later, soft again. I put the tire in water and it's leaking through the top around the valve area. Would applying the sealant directly to the area around the valve stem work? Could it be defective? Anyone have any other solutions? ???

Thanks in advance.