Diagnosis
If the fan runs but no water collects, the compressor (the part that does the actual cooling and dehumidifying) isn't kicking on. This could be due to a cold room, a clogged coil, or a faulty start component.
How to Fix It
First, check the set point. Press the 'Humidity' button until the display shows a number lower than the current room humidity. If you have it set to 60% and the room is at 55%, it won't run the compressor. Set it to 35-40% as a test. You should hear a distinct 'click' and a deeper humming sound as the compressor engages within a minute.
If That Didn't Work
The evaporator coils inside might be frozen solid. Turn the unit off, unplug it, and let it sit for 12-24 hours to completely thaw. Before restarting, check that the air filter (behind the grille) is clean. A dirty filter restricts airflow, which leads to freezing.
Heads Up
These units have a minimum operating temperature. If the room is below about 65°F (18°C), the efficiency plummets and it may not run the compressor at all to prevent damage. It's really designed for warm, damp basements, not chilly spaces.