FSX PMDG B737NGX and CH YOKE

Hi wonder if someone can advise

Using Fsx with PMDG 737NGX  can't get my CH USB 3 lever Yoke to actionnthe Elevators correctly

plane either pitches right up or down. elevators never realign in centre position, I have them on Y Axis have calibrated with CH control manager and FSX calibrator tool but alas no change

Strange thing when I disconnected the Yoke and changed from my Windows Desktop Ultimate 64 bit to my

Windows 7 Premium 64bit  the Yoke works perfectly with elevators centering perfectly after either pitching up or down.

Wonder if its an FSX PMDG 737NGX problem or I'm failing to do something with the Yoke when using it with FSX.

My Specs

Windows 7 Ultimate 64 bits

CPU Intel is 4670

16GB

Graphics NVIDIA GeForce  GTX 760  2GB

Hard Disk SSD 120 GBs

FSX with accelerator

PMDG B737NGX

                                                    Many Thanks

                                                           Richard