It seems that the dis forums chat function uses flash technology. Ipad and iphone do not deal with flash at all, but you can participate in the chats with a program from the App Store.
There are several flash enabled browsers some are free but I went a head and paid 3.99 for the PHOTON BROWSER. after a little fiddling around it will work. Feel free to try one of the free ones they may or may not work and if you need any help I would be happy to respond.
Good luck