delete char offset

I want to delete a textstrings from a tekst field like:
</B>
</div>
<div align='left'>

I have written this handler:

on cleartags whattag
L = (the number of chars of whattag)-1
repeat while member("tekst").text contains whattag
delete char offset(whattag, member("tekst").text) to offset(whattag,
member("tekst").text)+L of member "tekst"
end repeat
end

This is the commands that I issue:

cleartags "<B>"
cleartags "</B>"
cleartags "<I>"
cleartags "</I>"
cleartags "<div align 'center'>"
cleartags "<div align 'left'>"
cleartags "<div align 'right'>"
cleartags "</div>"


BUT  THE div align TAGS IS NOT DELETED IN
THE PROJECTOR ONLY IN AUTHORING MODE!

WHAT CAN I DO?

Hoep you can help really fast.