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Unable to activate autopilot on 737-800

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I was flying on VATSIM today with the PMDG 737-800 from EGLL to EDDL. To make things a little bit more fun I simulated a severe engine damage that forced me to divert to EHAM.

Everything went as expected during descent until suddenly my autopilot disengaged for no reason on the right downwind to runway 27 at EHAM.
A/T was off all the time and I was carefully controlling the speed manually with my left over engine. I was in heading mode and I used LVL Change to descent from 5000 to 2000feet when the autopilot disconnected from alone. There were no heavy winds at this point and I did not change the speed excessively.
I set the airplane back on course regarding heading and altitude and I also trimmed it as good as possible before I tried to reactivate the autopilot.
No matter what I did the AP always disconnected immediately shortly after activation.

Since I was flying in the dark at night I had to rely on the F/D bars during my approach to find the runway.

Hopefully I have given you enough informations to guess the reason what prevented me to activate the AP again.
Any ideas?

Thank you very much!

Best regards Andi

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Just guessing, but stabilizer trim would be my first suspect.  Realistically, the simulator platform does not support asymmetrical thrust scenarios very well.  I don't think PMDG ever mentions having this feature, certainly not in their Introduction document.  Many posts abound regarding the lack of realism with V1 cuts as well.

Dan Downs KCRP

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Thanks for your reply!!

From my personal feeling I set the stabilizer trim correctly. The plane was flying absolutely level with the horizon when I tried to engage AP after trimming.

I know what you mean about the assymmetrical thrust situation on the PMDG. I opened a thread regarding this without a satisfying result a few months ago.

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