I have had issues with the order of parameters when calling a function in DMN. The point is that it seems unpredictable. See also this thread at zulib 

In the reproducer I created, I wasn't able to reproduce the erroneous behaviour I had in my project. However, it still shows that there is something fishy going on. In the reproducer, the order of the parameters do not seem to matter at all. That should not be possible in my opinion. In the reproducer, the types of the parameters are disjunct. That might explain this behaviour. But in examples where the types are the same, the order is the only way to specify the call in a correct way. So order matters!

Reproducer: https://github.com/hanjoosten/KOGITO-8718