Can not install the theme

When Install the them the following error massage appear.

Downloading install package from http://ww.wp.xz.cn/themes/download/suffusion.4.4.7.zip…

Unpacking the package…

Installing the theme…

Could not copy file. /home/banglaph/public_html/wp-content/themes/suffusion/skins/light-theme-purple/skin.css

Theme install failed.

Can anyone tell me about the problem !