Assuming the injector is good then he's not programmed it in correctly. It's very hard to do it correctly, and even when you do it 'properly' the code doesn't always take, especially if it has flagged up an injector fault code.

The fault code needs to be clear before you can add the injector code - and even with the correct Delphi kit it's not easy, not straightforward to do.

He needs to take it to a diesel specialist ideally.