AD9834 no output on IOUTB only on IOUT

Hi there,

I'm currently evaluating the AD9834 with the respective CN0304 EVAL Board. If I interface the DDS via SPI with my microcontroller, it does not generate output on IOUTB (the filtered output), only on IOUT. If I connect it to my SDP-CB1Z DSP Board with the respective GUI, it works on both pins. 

Any suggestions?