somendu,
What we should check is that you have the “tslint” dependency on your package.json file, we could also verify that you have tslint enabled on your CodeMix settings, to check this, go to Window -> Preferences -> CodeMix -> Settings -> Workspace Settings in here on the text field type tslint, you should have a setting named tslint.enable and should be on true.
Best Regards
Ignacio