C4GP 1.6hdi diesel won't start!

Hi All, my c4gp was becoming noisy due to fuel injector seal worn off. So I replaced the seal and put everything back as before. Now I try to start the engine, but it won't start. Anybody knows if there is anything required to be done before starting the engine.
I tried to prime the fuel but it did not help
Any help will be appreciated.
Thanks in advance
Nathan