Thank you. So it looks like there isn´t any possibility without drawbacks.
I already had the suspicion that the dynamic light in itself could be the problem.
But now with that confirmation I can work around that for the moment.

But isn´t there any possible way with Acknex to have visible bumpmaps with
lightmaps with still useable dynamic lights?...

Would it be possible to use the static lights somehow, perhaps through the lightmaps, and still have it able to react to dynamic lights additionally?
How do other enginss have their levels bumpmapped with lightmaps AND working dynamic lights?