[TYPO3] BE Language NOT updating

[Surajit Kayal]

Hi List,

Have a website with:
- Typo3 4.0 installed
- Language Pack (Dutch) - csh_nl installed

 From "Setup" module when I am trying to update the BE language to 
"Dutch" the following message is displayed:
"The selected language is not available before the language pack is 
installed. You can use the Extension Manager to easily download and 
install new language packs."

Please Help !!!

Thanks and regards,
Surajit Kayal
Srijan Technologies, India.