Updating a BLOB with a URL

I'm using PHP to run a loop of MySQL queries that should update the
blobs with small image files, but it doesn't work. I'm thinking its
because I am running the queries remotely, because the MySQL
documentation seems to only upload the files locally, is there any
difference?

$fileURL is in the form
'http://www.host.com/imagex.gif'
where x is 1 - 395.

Query:
UPDATE $dbTable
SET content=LOAD_FILE('$fileURL')
WHERE id=$x