The problem might be that the reset signal is synchronous in nature, thus needing a clock pulse after applied and kept high for a certain time (see datasheet). You may use some FFs or a Pulse Converter component.
Thanks for your answer.
Yes I have read about the FF story but I would expect that there is a way to do it without any additional components (using the API of the module). In the end it would be ok to use a control-reg or writing a small user-module but this issue bugs me and I want to solve it in Software (without setting registers manually ;)
EDIT: The Pulse converter is actually exactly what I was looking for, thanks!