SimpleTech Simple drive Problem

I have a simpletech simpledrive enclosure which I have filled with a 250GB drive. I formatted the drive to be HFS+ (Journaled) and confirmed that it worked on my computer. Every time I hook it up to my airport extreme, it says the disk need repairs and the log also says that the disk needs repairs and then fails to mount. Verifying and repairing the disk give no errors. My internet search shows that a previous firmware had problems with simpletech drives. Does anyone know is 7.4.2 still does? All other drives I have hooked up to the airport work fine. Thanks.