[Wolves] Prob with thumbnail create

[Wayne Morris]

I've got a line in one of my php scripts that did work before I moved 
servers:

copy( $newphoto[ $i ], "{$IMAGE_DIR}/{$photoid}.jpg" );
makeThumb( $newphoto[ $i ], "{$IMAGE_DIR}/thumb/{$photoid}.jpg" );

Now I get the photo in the image directory, but not the thumb in the 
thumb directory.
Permissions for thumb seem ok, so I guess its the makeThumb routine.
Where can I start to debug it?

Cheers