The Elite App on the PS3, PC & Xbox 360 all have problems. They are extremely glitchy and the majority of the time they don't work but your best option is the online page through a PC or Laptop, maybe even a tablet or smart phone would work. I know when I was joining the clan I wasn't able to find the clan on the Elite App but it's easy enough eventually, they have the ability to send you an invitation to the clan. It will work basically just need some patience.