English 'pound' signs

Why aren't we able to use the English pound sign sometimes?

Everytime i try to use it i get an error message saying that the HTML format is wrong or something :/

(It seems to work sometimes but very rarely)

For special characters, you have to use the HTML equivalent in HTML mode.

www.gamespot.com/pages/forums/show_msgs.php?topic_id=26762461

EDIT: Oh and I don't know why it doesn't automatically convert them on GameSpot. TinyMCE (which is what they use as the WYSIWYG editor) does it just fine, but they stripped something from it on the forums.