NGUI elements are being shown as black area on iPhone4 and iPod4

I am using the NGUI elements and these are working fine on iPad and iPhone 5. but when I run my game on iPod4 or iPhone4 all the NGUI elements are being turned into a black area of size of their respective element. Can anybody tell me, why it is happening. Please guys help me out of this.


I have found the problem. It is device related. On iPod4 and iPhone4 we can not use the NGUI ATLAS of 4096x4096. There is a limit for texture resolution being used on these device. I have just turned my NGUI ATLAS of 4096 x 4096 to 2048 x 2048 .Now it is working fine. But I had to make all NGUI elements again as by changing the resolution the mapping of NGUI elements has changed. So I added new atlas (2048* 2048) and assigned the respective image to all NGUI elements.