Sharing WiFi Not Working

Hi!

I'm having trouble sharing my internet using my macbook pro. I go to system preferences, click on sharing and tick the internet sharing box. It then asks me if i want to turn wifi on, I say yes and then it asks me if i want to start internet sharing. I say yes again but then instead of producing wifi, it just connects to my neighbour's wifi. I used to be able to share the internet but now it's not working. Any idea how to fix this?

Thanks in advance!

You usually have to choose the source connection to get the internet connection from and then push it out another interface which you can choose from the sharing pane in system preferences. So if you have an ethernet connection to your mac, change the share your connection from menu to ethernet and then tick the wifi box under that.