No Filter works on ADAU1701

Hey Everyone,

I've spent more than one day in trying to solve this problem. Looking forward for your advice:

I'm developing a 2-ways battery powered monitor loudspeaker containing a ADAU1701. The Setup includes some functions controlled by GPIO-Pins. As I had struggles setting up the correct crossover I removed all but the basic features from my program. So basically I'm trying to merge both stereo signals into one and later seperate for a woofer and a tweeter at a 2 kHz point. Later I'd like to add an EQ.

BUT:

No filter seems to work. Whatever Filter I set, I can't notice any difference. When I download the programm to EEProm there will not be any output on any DAC, that has a filter in the signal path before. When I use the "link compile download" I have an output, but any filter settings I adjust won't have any effect.

I attach a very basic setup I'm trying to get to work right now:

I appreciate any help!