D600 with WU-1B - Cannot get it to work

I can get the Wu1b to work for a pic or 2 and then it disconnects and the blinking codes dont work like the instructions. I am using with Iphone 4s. In settings Wifi, it shows the network for the Wu1b and i tap it and it puts a check mark by it and in less than a minute it changes and connects back to my house wifi network, dropping the Wu1b network. Have spent lot of time trying to get it to work, but have become very frustrated. Do i have a defective one, or is it just this quirky? Any comments are appreciated, especially if you have experienced this or similar and have figured out how to connect solidly. Thanks.