I was validating my markup in doctype html 4.01 strict, and this is the error it gave me.
You have used the element named above in your document, but the document type you are using does not define an element of that name. This error is often caused by:
\* incorrect use of the "Strict" document type with a document that
uses frames (e.g. you must use the "Frameset" document type to get the "" element),
* by using vendor proprietary extensions such as "<spacer>" or
"" (this is usually fixed by using CSS to achieve the desired effect instead).
* by using upper-case tags in XHTML (in XHTML attributes and
elements must be all lower-case).
* Line 266, column 13: element "CENTER" undefined. Did you mean
Here's the source code:
<center> <b>XETEX Business Systems Inc., 1103 Rocky Drive, Suite103, West Lawn, PA 19609<br> <a href="http://www.xebra.com">www.xebra.com </a> </b> </center>
That means that the <center> tag is an invalid element and not part of the html 4.01 strict doctype.
i.e. Remove the <center> tags and replace them with something that centers the contained text, but that isn't a center tag such as:
<div style="text-align: center"> your text </div>