The mixture is not fixed

We got the Eismaxx on Friday and put the cooling container as directed for about 8 hours at -18 ° C in the freezer. Then we have then mixed a soft ice cream mix for chocolate recipe from the enclosed manual, pre-cooled for an hour in the refrigerator and poured into the machine.
Immediately froze the mixture partially stuck to the wall, we were looking forward to a great smoothie.
20 minutes later, the mixture was still liquid. After 40 minutes had not done anything yet. After an hour, we finally gave up, and tilted away the liquid. The engine of the machine has become very hot.

So we have again done the still cold refrigerated container for 12 hours in the freezer, figured that the next day perhaps works better. On the same day we have touched a new mixture, and these again put in de refrigerator, also for 12 hours at 6 ° C.

The next day again the same game. The mixture just solidified not, we reingeschaut every 10 minutes. After 30 minutes we thought it is determined something, but we got fooled. Mix tilted away again.

Then we did the whole container for 24 hours in the freezer. The mixture for 24 hours in the refrigerator. Nope, it was again only colder, but not tight.

I have the cooling tank after an hour "work" out of curiosity times measured with an infrared thermometer, he -3.4 ° C at the bottom. I do not understand why our mix was not.

Anyway, the machine goes willy-nilly back to Amazon, a cold cream-milk mixture can I get in the fridge, but I do not need noisy machine.

Pro:
- It's fun together prepare the ice mix
- Fast cleaning

Con:
- Makes a pandemonium
- Motor gets very hot
- Cooler is pretty clunky and occupies a half in the freezer compartment
- Ice is not fixed