Airport Express

Bought an airport express from Yahoo Auction for nearly 50% off. Was very excited to get, but it turned out to be a pain in the to set it up. Original idea is to use the original wireless network, but add this airport express to stream my iTune music to the speaker. But once Airport Express joins the existing network, it cannot be found anymore by either computer, wireless router, or just anything. I was very upset about it. Apple makes good products, but just not everything is perfect. Apple's keyboard sucks also.