[TYPO3] New doktype and connection to tree root problem

[Pierre Rouwens]

Hi listers,

I"ve created a new doktype, adding it in $TCA in the file extTables.php 
in typo3conf as i read ... and i can select it and view some DB fields i 
added. But when i wanna view it in FE ... i have a connection to tree 
root error. I surely missed something but what ?? i have googled it for 
a long time without any success... any idea please

Thanks in advance for any information

Pierre