I have seen a guy pulling people over in this mod and in the same version as i play in. all he does is flickering his lights and sirens while driving behind a civilian car, then they pull over mostly and he can go through procces without problems. But when i try to do the same. the civies just pulls over for like 3 secs and then drives away like nothing has happened, just like in the unmodded GTA..

It looks so cool and fun so can someone tell me what im doing wrong?

thanks in advance! 

Shift makes people pull over.