I'm trying to upload images to the mediawiki installed on my site-thingy, but I keep getting an error message "Upload error: The file you uploaded seems to be empty. This might be due to a typo in the file name. Please check whether you really want to upload this file."

I think I've set everything up ok. for example:

# ini_set( 'memory_limit', '60M' );
$wgEnableUploads = true;
$wgAllowExternalImages = true;

I have a duplicate setup installed on my home pc with WAMP which uploads and displays images fine.

What am I doing wrong?