A <span> must be part of one of the elements described. It cannot exist out of its own. This is wrong:
Code:
<p>Paragraph one</p>
<span>A span on the loose</span>
<p>Paragraph one</p>
This is correct:
Code:
<p>Paragraph one</p>
<p><span>A span on the loose</span></p>
<p>Paragraph one</p>
or even:
Code:
<p>Paragraph one</p>
<div><span>A span on the loose</span></div>
<p>Paragraph one</p>
Otherwise you need to post an example of your file before we can say anything useful.