plugin error vb and itrader

[bjf2k]

i tried to install the mod" itrader" but when i import the xml file
it give me this error
Database error in vBulletin 3.7.2:

Invalid SQL:
ALTER TABLE usergroup ADD itraderpermissions int(10) UNSIGNED NOT NULL default '0';

MySQL Error : Duplicate column name 'itraderpermissions'
Error Number : 1060
Request Date : Monday, June 30th 2008 @ 03:58:45 PM
Error Date : Monday, June 30th 2008 @ 03:58:46 PM
Script : http://www.fusionaw.com/forums/admin...=productimport
Referrer : http://www.fusionaw.com/forums/admin...?do=productadd

MySQL Version : 4.1.22-standard

anyone can help me out