[TYPO3] TCEMAIN.clearCacheCmd problem

[Bas Heutink]

Hello list,

I have a problem that when I add a tt_news item it is not displayed in 
the frontend.

Now I read on the internet that this is a solution:
TCEMAIN.clearCacheCmd = all

But somehow the clear cache command does not work with me.
Does anyone know why the clear cache command refuses to function?

Regards,
Bas