scrolling to select someone to stop

Hi,

I recently reinstalled GTA IV through Steam and downloaded LCPDFR 1.1. I thought I use to be able to lock onto a ped with the red and blue flashing dot and scroll with the mouse wheel to select the correct person you wanted to stop and question(without a weapon). Now whenever I lock onto someone without a weapon and scroll it just zooms the camera in and out. I've tried to find in the keyboard/mouse mapping to disable the zoom but have had no luck. 

Can somebody help me as this is frustrating especially when I do foot patrols of Star Junction and other high populated areas

Liam