Bulk adding avatars

I am trying to bulk add avatars to users directly in the wp_usermeta table by adding the following rows:

<auto-increment>	<user-id>	simple_local_avatar	a:3:{s:8:"media_id";i:230;s:4:"full";s:78:"http://site-root/wp-content/uploads/2014/01/filename.jpg";i:96;s:84:"http://site-root/wp-content/uploads/2014/01/filename.jpg";}
<auto-increment>	<user-id>	simple_local_avatar_rating	G

– for the sample above I haven’t updated the string length in the serialized entry

if I do this nothing happens, though, if I manually choose the same picture from the Library the avatar works even though there’s the same row in the db. Is there somewhere else where I need to add/register something?

http://wordpress.org/plugins/simple-local-avatars/