Foren / Cotonti / General / Upgarde Problem

Hi,
I'm want to upgarde my seditio to cotonti but ı can't do this.
When I enter upgaerde sql on phpmyadmin give this error:

/* Rendered cache support */ ALTER TABLE sed_forum_posts ADD fp_html TEXT NOT NULL DEFAULT  '';

#1060 - Duplicate column name 'fp_html' 

I'm waiting your ansver.
I'm sorry for my english