Why my Sony Xperia will not connect to my home wifi, the rest is ok ?

I have a home wifi but i cant connect to my xperia miro, my other devices are all connected ok. however whatever I do it will not connect although it shows an excellent signal......http://www.marbellalink.com/1/post/2013/01/why-my-sony-xperia-will-not-connect-to-my-home-wifi-the-rest-is-ok.html