Airport Express won't extend connection from Extreme

I have tried to set up my express to extend the connection from my Extreme, unfortunately using Airport Utility has not helped at all. First i have problems finding the express even after a soft restart or hard restart, eventually i connected it via Ethernet. After following the Airport Utility settings or doing it manually it restarts and Utility informs me it can not find the express after restart. first off i wasn't experiencing this problem when i first started the problem that was occurring was when the express would extend the wireless but not the actual internet connection. Meaning the bars would go to full on my computer under the same wireless name but yet there would be no data connection. please help me im going crazy because iv done this plenty of times and its worked and now at my own house im having problems.