What could be wrong with the compost bin?

There is no worm.
In many cases, even if you can't see it, there will still be worms in the compost bin.
If there are no worms in your compost bin, you can buy them from nurseries or DIY stores. Another option is to get a handful of worms from your neighbour.

Even if there are no worms in the bin, composting will still take place. However, the process will be slightly slower without the worms.

The compost is too wet.
If your compost is very wet, it is probably due to an incorrect ratio of dry to wet material. To solve the problem, you can add dry material such as sawdust, dry garden waste, wood chips or dolomite lime. It takes a little patience and experience to find the right moisture balance, but in time you will achieve a well-functioning compost.

There are flies in the compost bin.
It's normal for flies, insects and small animals to be present in the compost bin. These small organisms are a natural part of the decomposition process and actually contribute to the efficiency of composting.