I am running the lunar lander sample project. It worked first, but suddenly I got the message
WARNING: Application does not specify an API level requirement
It is impossible to start the project in the emulator after that.

I delete the project and create another one from the same lander sample project. The same thing happens. It works first, but suddenly I got the message
WARNING: Application does not specify an API level requirement

I try for the third time and the same thing happens. I have searched for solutions to this on forums, and the advice is usually to add a filter with "android.intent.action.MAIN" and "android.intent.category.LAUNCHER". This is already in the Manifest XMl file. How can I proceed to make it work? Shouldn't the sample code work in the emulator? This is the printout from the console:

WARNING: Application does not specify an API level requirement!
[ Device API version is 8 (Android 2.2)
[ HOME is up on device 'emulator-5554'
Uploading LunarLander.apk onto device 'emulator-5554'
Failed to upload LunarLander.apk on device 'emulator-5554'
java.io.IOException: Unable to upload file: null
Launch canceled!

I think I solved this problem. I had created a new project from the sample project, which probably caused the error. There were no errors like this when I imported the sample project instead.