Timeout Error for getsnapshot(obj) function?

I am using DFK 33UX290 camera. My matlab version is 2015b. My program looks like this:

obj=videoinput('winvideo',1,'RGB6_640x480');
set(obj,'TriggerRepeat',inf) ;% set graphics object properties
set(obj,'ReturnedColorSpace','rgb');
obj.FrameGrabInterval = 5;
start(obj);
data = getsnapshot(obj);
flushdata(obj);  
imshow(data);
My program is OK for 'RGB6_640x480'. but when I change the format for 'RGB24_1920×1080', it shows Timeout Error on getsnapshot() function.
Also, I changed the obj.Timeout properties, but it becomes very slow, it does not work properly!