I am not sure how does the wallpaper size work..I uploaded 3 wallpapers but i can only see 1 wallpaper in my vita.

details of wallpapers below.

1st wallpaper
dimensions : 1600 x 1200
can view on my vita



2nd wallpaper
dimensions : 960 x 720
JPEG
cannot view on my vita



3rd wallpaper
dimensions : 1024 x 768
PNG
cannot view on my vita

whats wrong yea??