Wifi wont detect!?

I have a Macbook Pro..when i take it to work i always sit at this table where i get wifi connection!(acroos the streets wifi).. My laptop does not even detect the connection but my sisters macbook and my other pc does and connects perfectly!.. Iv called apply a couple of times they told me to reset network settings.. done that 10 times...then i resetted the PRAM...done that 3 times. Iv tried those two.. i need some help on connecting to the internet.. it doesnt even detect the connection..my mobile phone even detects the wifi..This is very disapointing that a $3000 laptop not working well!!! please help