If the cloth is between the light and the chams UVB isn't getting through, and if it is the chams would have to be like 1 or 2 inches from the top to get it. Even finer screen cuts down UVB quite a bit so imagine what cloth and screen will do to it. Have you seen them drink yet? and were the yolks completely absorbed? They could be slightly underdeveloped but if they appear to be normal size I doubt it. Good luck.
Justin
Also if the cloth makes the cage darker than usual they may actually think it is sunset or nightfall and just be actually sleeping like normal. When you get the linear tube let it go unfiltered on them, see if they perk up and seem more alert.