Can't lock screen

Hi
I’m using openSuSE 13.2. The lock screen button doesn’t appear anymore.

How I can fix this?

If you right click
Do you see the option?

Is this KDE?

I’m using Gnome. In KDE I can lock it without any problems. But I have to use some application that are not compatible with KDE, So I have to use Gnome instead.
I Gnome, I can’t lock my screen. I don’t know what happened, but some days ago I could lock the screen, but now the lock screen button doesn’t appear anymore.

Did you originally install KDE and added the Gnome pattern later
If so, did you switch the session and window manager settings?

I installed them both during the installation of opensuse.

You may not understand me

Please check
https://dl.dropboxusercontent.com/u/10573557/Display_window_Manager/window-manager-gnome.jpg
https://dl.dropboxusercontent.com/u/10573557/Display_window_Manager/display-manager-gnome.jpg