Black gauges in dual screen setup

Hi, does anyone have problems with flying the 737 NGX in a dual monitor setup where the second monitor is being used for the FO gauges.

After installation of an aircraft I usually use a second monitor for zoomed instruments like the PD, ND, CDU. After undocking the instruments I move them to the second monitor. But when I move the instruments into the second monitor they become black in PMDG 737NGX.

I added some lines in the FSX.cfg file as described in the introduction manual (WideViewAspect=True) and this solved a part of the problem. Now the instruments are there but they are smaller then the windows where they are placed in. I do use 2 different monitors, the primary has a resolution of 1680x1050, the second 1440x900. I changed the resolution of the primary monitor to 1440x900 but the images of the instruments are still smaller then the window in wich they are placed.

Does anyone has similar experience or knows how to solve it.

Thanks