[Theme: Clear Style 1.2] Background Image LOST

Hello All,

As a Theme I use the ClearStyle 1.2, there is an option to change the background. What I have done. but something strange happend.
I use also the Theme Tweaker PlugIn.

I went to the ThemeTweaker Settings to suppres the ThemeTweaker at the bottom of the page. After that the background image disappeared.

I have tried with in the Apperance Setting.
To remove the background and then save settings, then to re-upload the background image again to save it again. But still no background Image.
Even a completly different image file will not appear as a background for the Theme.

What to do???

Thanks in advance