Check every single option in the graphics tab of the options menu. I think there is some lighting option you have set lower than your friend. I'll look for you when I can.
try setting your draw distance to a higher distance
When you press your light keybind, can you see the light on other bricks then?
Open up the options menu, go to the "Advanced" tab.Make sure "Animated Lights" has a check mark next to it.
Did you get it off of the forums? If so, I think your file is corrupted, and you should redownload it.If not, check over your render distance type stuff for any low values.
NoeditWas this at your server, or your friend's?