I was trying to install the addon Headcount to the guild website hosted by wowstead.com when it failed to install and I was directed to the error page I would like to use Headcount to update all guild raid details is there any light you can shed on this problem please.

You'll want to post here:

http://wow.curse.com/downloads/wow-addons/details/head-count.aspx

or even better create a ticket here:

http://www.curseforge.com/projects/5919/tickets/