[jQuery] Why is IE messing with my mind?

Hi,
On PC IE (v. 7.0) only, I'm getting a JS error on line 9, saying
"Error: Expected identifier string, or number." Here's the code
function slideIn(id) {
hideAllSubNavs();
if (IsHidden(id))
toggleDiv(id);
$('#' + id).animate(
{
left: 0,
}, // line 9
"normal"
);
} // slideIn
This, of course, works fine on Firefox. Could someone tell me how to
heal the pain on IE?
Thanks, - Dave