No shared folders appearing in media player.....

Hi there, I have enabled file sharing on a folder on my HD2 on my imac yet it is not accessible in the media player on my atv…I have set up a share for my imac but i cant see any other folder when i navigate past my imac in the atv

sorry if im doing something insanely silly im a total noob:D

I had the same but rebooted my modem and Time Capsule… and then Shared Folders appeared.