DIAGNOSIS If the fan is running but there's no water collection, the compressor likely isn't kicking on. This could be a few things, but the most common culprit is the room temperature being too low for it to operate efficiently.
FIX Check the room's ambient temperature. These units have a built-in protection that keeps the compressor off if the room is below about 65°F (18°C) to prevent icing up. Move the dehumidifier to a warmer room, or raise the room's temperature, and let it run for a few hours. Also, make sure the air filter on the back is clean—a clogged filter can restrict airflow and cause performance issues.
IF THAT DIDN'T WORK If the room is plenty warm and the filter is clean, listen closely. Do you hear a faint hum or click every few minutes, like it's trying to start the compressor? If not, there might be a refrigerant or compressor issue. Ensure it's been sitting upright for at least 24 hours after moving it, so the refrigerant can settle.
HEADS UP In a cool basement, it might run the fan but not actually dehumidify for hours if the air is cold. That's normal operation, not a defect. It's waiting for the air to warm up enough to start condensing moisture.