Not loud, but poor dehumidification

I've worried this device for my 15sqm large bedroom because at night the skylight strikes inside when it is cold outside. After the tip of my shutters installer, I should get me a dehumidifier, I did this and found this unit here on Amazon.
After I bought it, it came to after a few days. First, I was pleasantly surprised about the very simple and well designed housing.

Shortly after, I tried out the device by I anschaltete it go just before bed. Thus, the device ran all night.
In the morning I woke up then and noticed that the skylight was still fogged. I've tried it a couple of nights out, and sent it back eventually to Amazon.

Perhaps the machine is really efficient only for wardrobes.