Problems installing membership plug-in

hi!

on my first attempt to install the membership plug-in i was unable to add a new membership level.
i read through the forums and saw that some other users had success by removing the membership items from the database and reinstalling the plug-ins.

i deleted the membership fields from the database, but when i tried re-installing the plug-in the fields were not being added back into the database. i checked the wp_options and deleted two items that had the "M-" in front of them.

now when i tried reinstalling the plug-in, i get the following error messages:

Warning: include_once(/home/fortknox/public_html/wp-content/plugins/membership/membershipincludes/classes/upgrade.php) [function.include-once]: failed to open stream: No such file or directory in /home/fortknox/public_html/wp-content/plugins/membershipincludes/classes/membershipadmin.php on line 87

Warning: include_once() [function.include]: Failed opening '/home/fortknox/public_html/wp-content/plugins/membership/membershipincludes/classes/upgrade.php' for inclusion (include_path='.:disappointed:usr/local/php5/lib/php') in /home/fortknox/public_html/wp-content/plugins/membershipincludes/classes/membershipadmin.php on line 87

Fatal error: Call to undefined function m_upgrade() in /home/fortknox/public_html/wp-content/plugins/membershipincludes/classes/membershipadmin.php on line 89

any ideas?

thanks,
sid barcelona