If you want your horizontal rule to be shaded you have to add the switch "noshade" to the argument. Why "noshade" to get it shaded? I haven't got a clue.
The "align" argument is unnecessary on FR. It defaults to centered.
<hr width="50%" size="10" noshade>
<hr width="150" size="150" noshade>
See the previous post on more HR fun...