Diagnosis
The chemical injector is either clogged or the inlet tube isn't submerged. It relies on suction created by water flow through the venturi.
How to Fix It
Detach the suction tube from the bottle. With the machine running on LOW pressure setting, place your thumb over the end of the tube. You should feel strong suction. If not, the injector nozzle is clogged. Use a thin wire to clear the small orifice.
If That Didn't Work
The O-ring on the injector fitting where it threads into the pump may be cracked, breaking the suction. Replace the O-ring.
Heads Up
Only use the soap injector with the black low-pressure wand tip installed. Using a high-pressure tip creates no venturi suction and can damage the injector.