Kiss a hundred frogs and you will find a prince. Right now the inventory is brutal. There is never anything wrong with submitting a backup offer as a fairly high percentage of short sale buyers backout, fallout or find other homes for a variety of reasons. Honestly right now is probably one of the most challenging times I have ever seen for any buyers, even tougher then the bubble years. What little inventory there is available is most likely distressed, investors are running around funnelling cash into any good deals out there, and you are fighting against very well qualified buyers.
Have patience, don’t get emotionally invested, and if you get to frustrated just sit out for awhile.
Finally, though this house may or may not come available to you, there will always be another one.