[TYPO3-english] Custom tags

[Pero Matic]

Hi. After upgrade to new ver. of Typo3 (previously i had some really old one 
with ActiveX RTE) my custom tags (ext. Custom Tags) is not working correctly 
anymore. The problem is that if i have a tag ie:

<sometag>foo</sometag>

that should be rendered as <td>foo</td>

it gets rendered in html as:

<sometag>foo</sometag>

I tried different settings with htmlarea RTE (allowTags etc. etc.) but 
nothing helped. Is there a solution for this beacuse my old web is not 
functional anymore :-( Thx!