mode based steady state dynamics problem

[dezsit]

Hello,

I'm working on a problem and should make a harmonic analysis for it. My problem is, that I have acceleration field as load. I prescribe it as gravity (DLOAD), with its components, and one of the component is in phase (varying cosinusoidally in time, real part) the other one is out of phase (varying sinusoidally in time, imaginary part). The simulation is succesfull, but I don't get any result. I get the mode shapes (from the frequency analysis before the harmonic), but I don't get any displacement or stress values for any frequency, in the harmonic analysis.
Do have anyone, any idea, what can be the problem?
I have made a small modell, for the verification of my problem, and it didn't work as well. I made not only mode based analysis, but also a subspace steady state dynamic, the result was the same. It works only, if I use steady state dynamics with direct integration. But my real modell is too huge to do this kind of analysis.

My material is linear elastic, with out damping at the moment.

Thanks for your help!