ceiling lamp

Hello there. I would replace the bulb of the ceiling lamp of my 2000 model 206 XT, but I could not disassemble it. I pulled a lot but I was afraid of breaking it. I would appreciate if you can help me with a pictorial or a technique.

http://forum.peugeotturkey.com /forum_posts.asp?TID=7279&title=206-tavan-lambas-nasl-sklr

There is an illustrated explanation on the link It will be more comfortable if you try it with a thin screwdriver

Thank you very much indeed. I looked at the old subjects quite a bit, but I couldn't find it. thanks again ..