[TYPO3-ttnews] Category Tree not visible in BE + starting point

[Thierry Brodard]

Hello,

Since I've upgraded to 3.0.1, the category tree ist not more visible in 
the BE.
The label "Category selection" is displayed, but no tree.

More: the starting point has disapear. After the update, no more 
starting point in the BE, for each instance of tt_news.

Please, help, because tt_news is intensivly used on this site.