new problem when i want add an article !

Sorry my english is bad but i try to explain my problem:

(Voila ce matin j'ai voulu ajouter un article a mon site et la je tombe sur un message que voici
Whenn i'd like to add an article I have this message:

I click on the no entry sign and then i had another message:
j'ai cliqué sur "effectuer" dans la colonne de droite (celui qui etais marqué en rouge avec un sens interdit),
"Warning: Creating default object from empty value in /home/httpd/c/r/o/croqgamelle/croqgamelle.franceserv.com/administrator/components/com_flexicontent/models/items.php on line 1460"

Since i cant add article or modify one of them!

What is the problem?

How to solve it?

Thanks

Lily

ps : i Have joomla 1.7 and i never change antyhing in the site recentrly

i cannot read the image,
but anyway install the nightly build that will be available by tomorrow

Regards