wallpaper_daemon - ImportError: No module named gtk

[erngab]

I tried to install wallpaper_daemon

$ ./wallpaper_daemon.py --install
Traceback (most recent call last):
File "./wallpaper_daemon.py", line 11, in <module>
import gtk
ImportError: No module named gtk

I do not know what this error, and what to do.

[erngab]

I install python-gtk2 OK