ERROR: Could not find a valid gem 'compass' (>= 0) in any repository

[Varun Sahu]

when i am trying to install compass it give me this -> 

ERROR:  Could not find a valid gem 'compass' (>= 0) in any repository

i am using grunt which inturn uses compass i guess 

when i fire grunt serve it shows me

Running "serve" task

Running "clean:server" (clean) task

>> 0 paths cleaned.

Running "wiredep:app" (wiredep) task

Running "wiredep:test" (wiredep) task

Running "wiredep:sass" (wiredep) task

Running "concurrent:server" (concurrent) task

    Warning: Running "compass:server" (compass) task

    Warning: not found: compass Use --force to continue.

    

    Aborted due to warnings.

Any ideas on how to fix this. Searched everything on google but it does not work