AddNew Plugin doesn't work

It doesn’t matter which Plugin I try I always get the following error message using the Add New Plugin function in WordPress. How do I fix this…Thanks…Warwick

Downloading install package from http://downloads.wordpress.org/plugin/counterize.3.0.29.zip…

Unpacking the package…

Could not create directory. /home/httpd/vhosts/harryhealy.com/httpdocs/wordpress/wp-content/upgrade/counterize.tmp