HTML Tidy Issue

Hello,
I would like to use HTML Tidy alongside mytaglib stuff, enabling me  
to highlight search words in a page.
This involves putting all user-entered content within  
<mytaglib:keywords> tags.
Unfortunately, despite having declared mytaglib as being a new block  
AND inline tag, Tidy still seems to remove the closing tag, creating  
internal server errors.
Do you have a solution to this?
This is my config setup for Tidy:
indent: auto
indent-spaces: 2
wrap: 500
wrap-asp: no
wrap-jste: no
wrap-attrs: no
wrap-script-literals: no
markup: yes
output-xhtml: no
output-xml: no
input-xml: no
show-warnings: yes
show-errors: yes
numeric-entities: yes
quote-marks: no
quote-nbsp: yes
quote-ampersand: no
break-before-br: no
uppercase-tags: no
uppercase-attributes: no
char-encoding: utf8
fix-bad-comments: no
literal-attributes: yes
new-inline-tags: mytaglib,sum,span
new-blocklevel-tags: mytaglib, sum,span
new-empty-tags: mytaglib,sum,span
new-pre-tags: mytaglib,sum,span

As you can see, I've tried everything!
Here's the tag's it's screwing up:
<mytaglib:keywords before="<span style='COLOR: red;'>" after="</span>">
	<USER HTML HERE>
</mytaglib:keywords>
NO matter what I do, Tidy always strips the </mytaglib:keywords>  
close tag.
I'd appreciate any help you can give.

Kind regards,

Nathan Trevivian
GateWest New Media Ltd
1st Floor, Aztec Centre
Aztec West
Almondsbury, Bristol
BS32 4TD
Tel: +44 (0)1454 203720
Fax: +44 (0)1454 203330
email:nathanielt@gatewest.co.uk
web: http://www.gatewest.co.uk



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