Sorry we missed your post but glad you solved the problem anyway and as mentioned above we don't close posts but like the OP to post their solution when they find the answer before we do
If you are supporting IE6 then concatenated id.classname (or classname.classname) dot notation structures are very buggy in IE6. What's worse is that they may appear at first to work but in fact they don't and are best avoided if IE6 support is required.
If not then ignore the above as they are quite useful also
An alternative would be to make the class more important than the id by either creating a longer path name using an id from a parent higher up the html, assuming there is an id available somewhere (which is quite likely), or if not by using important on the class itself.
That would ensure that the class has more weight but !important can be a double edged sword and should be used wisely and usually very infrequently.