Airport Express as range extender

I tried these settings using my airport extreme base station and an airport express to extend my network. The airport express disappeared from the utility and now has a flashing yellow light instead of a green light. what did I do wrong? Help

i've got an airport extreme with 2 airport expresses linked to it (all n). Both AX's are connected to sterios and are set up to 'extend network'. They are both 'green' and i can play itunes through them from the main mac (connected to the extreme) so all good. However - they are not giving out any signal and my laptop and iphone cannot connect to the network in the 2 rooms the Ax;s are in. Anyone got any thoughts because its stumped me! thanks

Ok so ive been using my neighbors internet because im subletting and I didnt want to set up a contract for internet service I wouldnt be able to use all of. Anyways, everything was fine until 3 days ago and then a message came up about me sharing and IP address or something like that, regardless I have my neighbors Network name and the password for it but when I go to connect on the Network page the dot next to the airport is still yellow instead of green. What is going on?! How do I fix this?! Can someone please help?!