Invalid Application Delete? J2ME

This can happen because of two reasons
1. General attributes not added to project. Do the following to achieve this
          Select project from project explorer > Properties > Application Descriptor>Attributes Tab > Use Add button

2. Important! May be beginners will miss this
          Select project from project explorer > Properties > Application Descriptor>MIDlets Tab> Use Add button to add MIDLet name and MIDLet class

MIDlet class is a unique class in your project which extend MIDlet as

MyMainClass extends MIDlet