karma command not recognised

I have node and npm installed, a node_modules folder in my solution folder with karma and jasmine installed.

When I check version of node i get : v4.0.0

When I check version of npm i get: 2.14.2

I have Karma-Cli installed

Yet every time I try to run a karma command, for example karma start (from the directory it is installed) I get:

'karma' is not recognized as an internal or external command, operable program or batch file.

Infuriating, any ideas?