Sir Alex Ferguson admitted his kids were taught a lesson as Manchester United crashed out of the Carling Cup. United were crushed 4-0 by West Ham in Tuesday night's quarter final ending their two-year stranglehold on the trophy and a 29-game unbeaten run. And Ferguson acknowledged his team which included Fabio, Jonny Evans, Chris Smalling, Bebe, Anderson and Gabriel Obertan failed to cope with the Hammers' onslaught. When you analyse it, the goals we've given away were too soft, said the United manager. We had a lot of young players out there and it's probably a lesson as we invest in that youth, but we didn't expect that. They were terrible goals to give away. They are too young to carry these type of mistakes as there were too many of them 20 or 21 years of age to carry these kind of mistakes and still win. Former United starlet, Jonathan Spector, scored twice in the first half to put Avram Grant's relegation-threatened side in control and Carlton Cole completed the rout with a double after the break. Having won the Carling Cup three times in the last five years, Ferguson accepted his team selection cost him the chance to make it a hat-trick of triumphs this season. We invest in youth, we have always done and done well over the years, he said. They will remember it, but it was a quarter-final tie and a really good opportunity of wining a trophy. West Ham had an early effort by Victor Obinna correctly ruled out for offside and Ferguson felt the perceived sense of injustice provided inspiration. The goals killed it. You can't just give goals away at this level. That first goal was a break for them. We were in control in the early part, played some good football. The thing that sparked it was the goal that was disallowed because it got the crowd up. It was clearly offside but they celebrated for so long. It spurred them up. Are United's youngsters up to the task? Have your say.