error: 'document.getElementsByTagName('...')[0].href; is null or not an object

Description

Hi guy's
I new with the drupal concept and not a php wiz ore a programmer, just a Sr. system engineer.
I started using drupal 2 monthe ago with the 4.6 version and the ajax.module and the ajaxspellcheck for this versions.
All that worked great.
Now i have made a clean install with drupal 4.7 cvs version and downloaden the ajax module from thox sandbox and the spellchek from cvs.
Installed then according the installation guide.
Links will show op no errors in the drupal log.
But when i post a new item and press spellcheck notting happends.
IE will give tehe following error;
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error: 'document.getElementsByTagName('...')[0].href; is null or not an object
Thats line 79 in de spellcheck.js
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Does somebody have any idea how i can solve this ?

Thanks Allot.

Http://www.QuikSoft.nl