Modifiers cannot be applied to multi-used data?

I got this error message after using the mirror modifier. After modifying the model, I wanted to apply the mirror, clicked on apply, and got the error message in the title (nothing happens).

I made several searches in this forum and on google but came up with nothing.

What to do? :confused: I can stitch the model halves by hand but since mirror has autostitching that would be nice.

Use U in Object mode to make it Single User.

%<

Thanks will try this asap - whew it was doing my head in.

After long search found link to this thread in google and it introduces the OOPS chart for understanding/viewing ‘users’
http://blenderartists.org/forum/showthread.php?p=727111