Why I am getting the following error??

You don't have permission to access /modules/publisher/admin/item.php on this server.

Please note:
1- I am the admin with all the required permissions
2- I am the owner of the article that showing this error
3- I did create the article in the past and modified it, but now it is showing the
bove message whenever I try to edit it or add hyperlinks or even if I want to
change text color.
4- I use xoops 2.5.5
5- I use Publisher 1 Final (2013/7/18) by Trabis (www.Xuups.com) GNU GPL 2.0

please guys any help would be appreciated in advance.

You are using a very old version.
Please download the latest version here
http://sourceforge.net/p/xoops/svn/HEAD/tree/XoopsModules/publisher/trunk/