Clio Starting problems?

Hi,

I have a 1999 Renault Clio Diesel to which I have just had to change the ignition barrel. (I've changed the key blades to match the original too)

When attempting to start the engine it refuses to turn over or even make a noise.

With regards the Immobiliser light it flashes until I insert the key then it stays on... It does go off when I attempt to start it so I'm assuming it's not the Immobiliser?

Any help would be great!