android emulator disconnected error

These days i am studying Android, and i read the intruduction from IBM developer web site, but when i import the FlashLight project for test and have a look, the disconnected error occured, googled a long time, finaly i found a resolution.

 

I guess it is because the android version of the project is not compatible with the target Android Virtual Device,

so my solution is: run->debug configuration-> Target->Manager->New->create a new version of Android Virtual Device, so it worked fine.