GP4 dont want run in my second screen!

Hello Mates, i have a small problem, yesterday i installed 2 screens, a 22" Benq LCD for windows only, and Viewsonic G90F+ for gaming..
With only the G90 im able to play a 1920x1440, but with the lcd togheder gp4 only runs on the primary(LCD).
In rf and FSX i can choose wich one i want to run, in rf when i execute the game, it loads automatically in my G90, FSX the same.
In GP4 i can see in the graphics menu that i can change the screen(there are 2 options), i can choose the two, but no effect, it remains on the lcd..
Is there something that i have to change?

Thanks for the Help!

GP4 might not be able to handle this sort of setup. Remember its a relatively old game in comparison to new games. But maybe there is a work around. Unfortunatly, not knowing the equipment, can't really be of much help.

Yes... i tried lots of times, and maybe gp4 is not able to handle my config Thanks