That's because the available offsets are top="offset=x"; and left="offset=x"; There is no right offset property. Besides, using a screen position left and trying to set a right offset is really not compatible. If you want the menu to be 40 pixels toward the right side after setting a left screen position just do, screenposition="left"; left="offset=40";, though I don't know why you wouldn't just set it as left=40; which places it 40 pixels toward the right side from the left position of 0 which is the default position of the menu. 0px is actually 0 after whatever your left margin is, so if you set the left margin at 0px then the menu position default is 0px at the left, if the left margin is 5px, then the default left of the menu is 0px after the 5px margin, and so on.