Internet sharing on mac (lion 10.7.3)

[regex]

Hi all,

I have an ethernet connection and I want to use internet sharing feature on my mac. In system Pref -> Sharing -> Internet sharing, I can see a message saying internet sharing is on. But the drop down for "share your connection from" is empty. Its actually greyed out completely. Same with the field "to computers using". This field has wi-fi, firewire and etherner listed but they're greyed out. How do i enable them? Is it some permission issue?

 

[justperry]

There is a padlock, is it locked, if so unlock first.

 

[iThinksimple]

There is a padlock, is it locked, if so unlock first.

just added the pict,
see the lock icon at the bottom left,