Eclipse indexing not working

Question

I am using CDT in Eclipse 3.5.2 Galileo in Ubuntu.

My eclipse\'s indexer doesn\'t work at times. By that I mean when I ctrl click a function it says

Answer 1

Convert a project to C or C++ nature:

Right click on project: New >  Convert to C/C++ Project

In "Convert to C or C++": Choose C/C++ Project

In "Project options": Check "Specify Project Type"

...Project Type: Choose "Makefile project"

...Toolchains: Gross GCC