I am running Eclipse Juno SR 2
I had a similar problem. To fix the issue go to Run-> Run Configurations…
- If there isn’t create a new run configuration (top left)
- Under Android tab: browse and select the project you want to run
- Under Target tab: select Always prompt to pick device (or) you can pick automatic launch.
Similar solution can be applied to the Debug by going to Run-> Debug Configurations…
Update:
I realize this is beyond the scope of the question but if any new developers are coming to answer then I would suggest switching to Android Studio from Eclipse. AS is the official Google supported IDE for Android development and much nicer to use.