Again, I do not see anything fundamentally wrong with your code.
Let's start at the beginning and work through this step-by-step.
What is the system clock frequency?
What is the DDS tuning word?
It would also be useful if you could provide two frequency spectra:
1) One with SpurKiller disabled.
2) The other with SpurKiller enabled, harmonic=2, gain=maximum, fundamental off
Then we'll go from there.
