How to turn on one of MyEclipse important function

Question

I'm using MyEclipse for writting Java code, but i against a problem that before when i click on a variable then Eclipse automatically show me this variable where has been used in this class, but now suddenly doesn't perform this function, if any one knows about this problem please tell me how to activate it. For better understanding my question please refer to picture below:

Answer 1

In Eclipse go to

window > preferences > java > editor > mark occurrences 

and select everything there.