WordPress MU

i have install in 20 times. but i can't to resolve the problum is i cant to use the plugins in mu-plugins or plugins.
this is the picture that the plugins panel in admin control panel, whatever many plugins copy to the folder are always look this picture.
i have copy widgst and list-all plugin to mu-plugins.
please help me . thanks a lot!

<img src="http://pic.chinawawa.cn/albums/userpics/10005/plugins.JPG">

make sure that you have the box checked to enable plugins under site admin -> site options

thanks for replay!

yes , i do .

if not chose this option

the plugins tab will not list in the top.

this afternoon, i have test the other 20 times .
maybe i found what happen with the problom.

What's the problem? Interesting.

maybe i found , but now.
i dont know what plugins can be used in mu-plugins folder.

maybe the permissions are wrong?

Plugins dropped into the mu-plugins folder are automatically activated, and will not show up in the Plugins page.

Widgets will work in the mu-plugins directory if you follow the instructions from this page.

I've also managed to get List All to work in mu-plugins without any modification to the code.