Installation Problem, CB v. 1.3.1, Joomla v.1.5.22

Hello i am trying to install CB on my site bu i am receiving this error

Unable to create directory '/'Unable to create path for /install_4d3e1fa413cfc/index.html
Installer - Error
Uncompressing /home/mysite/public_html/administrator/components/com_comprofiler/pluginsfiles.tgz failed.

what should i do to fix this? i tried what have been said in readme - new install.txt file but still no solution, i have installed cb previously on many sites but this is first time i am receiving this error.

i solved the problem sorry for openin this topic, after installation i uploaded expert files from ftp, overwriting existing files and deleted the pluginssfiles.tgz. hope this solved my problem because component is working now.