The AT&T S4 has a locked bootloader. If you took the latest OTA, the current root methods got closed off. No Odin, no Loki. If you're in that boat, you're stuck with stock ROM until a new crack is discovered. The way to tell is to look at your baseband version. If the last three characters are MF3, you're locked up for now. If you have MDL or previous, you can achieve root. I'm rooted, and working with my Developer friend to break this puppy wide open. Right now I'm in modified rooted stock.