GTA4 help pls

[Breakfloor]

im stuck on the one where you get a sniper rifle and have to defend packie (thats his name) but he runs and he dies straight away.

[Niko Bellic]

When it says he's in trouble, look down and someone should be grabbing his gun, head shot them or w/e.

[Meanies]

They're by the bin near where the people drive up. Then just shoot the rest of them - they don't try and attack him from close up.