Valid XHTML 1.0 error question

[Boofo]

Can anyone tell me why this line is not passing XML validation and how to fix it? I can get rid of the error if I use span instead of div but I need the padding for these links.

<strong><div style="padding:4px;0px;4px;0px;"><a class="sitemap" href="' . $vbulletin->options['bburl'] . '/forumdisplay.php?f=' . $forumid . '" style="font-weight:bold;font-size:12px;" title=" ' . $forum[title] . ' ">';

I'm using it in a php file and it works but I get this message on validation:

document type does not allow element "div" here; missing one of "object", "applet", "map", "iframe", "button", "ins", "del" start-tag .

The mentioned element is not allowed to appear in the context in which you've placed it; the other mentioned elements are the only ones that are both allowed there and can contain the element mentioned. This might mean that you need a containing element, or possibly that you've forgotten to close a previous element.
One possible cause for this message is that you have attempted to put a block-level element (such as "<p>" or "<table>") inside an inline element (such as "<a>", "<span>", or "<font>").