Hi-- I'm stuck on a mySQL query using ON DUPLICATE KEY UPDATE.

I'm getting the error:

mySQL Error: 1062 - Duplicate entry 'hr2461809-3' for key 'fname'

The table looks like this:

id int(10) NOT NULL default '0',   
picid int(10) unsigned NOT NULL default '0',
fname varchar(255) NOT NULL default '',  
type varchar(5) NOT NULL default '.jpg',  
path varchar(255) NOT NULL default '',    
PRIMARY KEY  (id),  
UNIQUE KEY fname (fname),  
KEY picid (propid)  
) ENGINE=MyISAM DEFAULT CHARSET=utf8;  

And the query that's breaking is this:

INSERT INTO images SET picid=732, fname='hr2461809-3', path='pictures/' ON DUPLICATE KEY UPDATE picid=732,  fname='hr2461809-3', path='pictures/' 

I'm using a very similar query elsewhere in the app with no issues. I'm not sure why this one breaks. I expected that when the UNIQUE KEY on fname gets violated, that it would simply update the row where the violation occurred?

Thanks for any help