Encountered Instrument trace error : Target failed to run : Failed looking up pid of launched process

Appium was running fine till date with other app i used for automation but encountered this problem today
Encountered Instrument trace error : Target failed to run : Failed looking up pid of launched process.
What happens is app tried to open itself in the simulator,but pops up and goes back and forth .

and along with that other issue found if “Instrument Crashed on Set Up”. The app runs fine on real devices (all version of iOS in iphone and ipads)

Using : Xcode :6.0(6A313)
Appium 1.4.0 (Draco)