[jQuery] Error in IE, works in Firefox

[hydra12]

I'm working on a game in my (spare) time.  It works in firefox, but
not in ie.  In my code, I assign a variable:

board = $('#board');
board.hide();

This works in the latest firefox.  In IE 6 and 7, I get Error: Object
doesn't support this property or method

Any ideas?

Thanks!
hydra12