Missing requirement: Android Native Development Tools 20.0.0.v201206242043-391819 (com.android.ide.eclipse.ndk.feature.group 20.0.0.v201206242043-391819) requires 'org.eclipse.cdt.feature.group 0.0.0' but it could not be found 에러
- Go to Help/"Install New Software..."
 - Click on "Available Sofware Sites"
 - Search "http://download.eclipse.org/releases/indigo and enable it
 - Search "http://download.eclipse.org/tools/cdt/releases/indigo and enable it
 - Come back to Help/"Install New Software..."
 - Check "Contact all update sites during install to find requiered sofware"
 - Install ADT Plugin
 - IT MUST WORK!!!
 
http://stackoverflow.com/questions/11419858/installing-adt-on-eclipse