Not enough information to even make a guess - do you have one of the problems listed below?
Cloud desktop problems
Sign Out When Sign In http://forums.adobe.com/thread/1450581?tstart=0 may help
-and 'looping' https://forums.adobe.com/thread/1504792
BLANK Cloud Screen http://forums.adobe.com/message/5484303 may help
-and step by step http://forums.adobe.com/thread/1440508?tstart=0
Mac Spinning Wheel https://forums.adobe.com/message/5470608
-Similar in Windows https://forums.adobe.com/message/5853430