iCloud photo libary doesn't work on LTE/3G

I just decided to use iCloud Photo libary because my photos took up too much space on my phone. It seems to work on.....wifi only, I have about 12,000 photos and i was connected to wifi when uploading these pictures but the second im out of a wifi zone and on LTE trying to load any picture it shows a little "!" in the bottom corner and never loads the picture. Help?