In order for the mouse wheel to function as a tool to zoom in our out a view point, ensure to have the functionality active.
See this below tutorial for more information.
Activating or Deactivating Mouse Wheel Zoom
The mouse scroll wheel is traditionally centered between the left and right mouse buttons, as displayed below.
Zoom in
When in a Plan view, Elevation view or Perspective view, to zooming in is achieved by simply rolling the mouse forward.
Zoom out
When in a Plan view, Elevation view or Perspective view, to zooming out is achieved by simply rolling the mouse backward.