How do I find my WEP pphrase on my SMC router?

Well I recently got a SMC Router SMCD3GN model and my ISP hooked it up using a WPA-PSK connection. I wanted to hook up my stuff to it and found that some of it doesnt connect unless is WEP, like my Nintendo DSi. I went ahead and did a reset and changed the encryption to WEP and saved it, and its says that it has been saved but when I want to look at it, it only shows dots. I've tried resetting to factory settings a few times and the result is the same. I tried putting my combination and it doesnt work and there isnt a tab that can show me the pphrase at all on my router. Any ideas?