The toolchanging spindle hovers above the tool holder when picking up or returning the tool.
One of two issues is likely in play:
There is inadequate air pressure to the toolchanger (this is likely if there is no tool currently in the chuck -- the spindle is going to do a pickup).
Alternately, there is an issue with the tool sensors.
If the air pressure is adequate (90 psi or higher):
Check the large ribbon cable that goes between the toolchanger control box and the controller.
If the machine is a MP/LC+/Premium controller, the cable will plug into the PCI card or Riser card next to the PCI card. On fresh installs, this is a common problem. If the machine is an LC/LP controller, this cable will plug into the LC control board. This is typically not a problem on LC/LP controllers, as this cable is attached at the factory.
If this cable is plugged in properly, the next step is to check the sensors for the toolchanger.