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Additional: A new issue in WordPress 2.6 occurs when you have a custom directory for file uploads. The upload will work, but the link/thumbnail link will be wrong and so the image won't appear. This is a bug which can be fixed in one of two ways (either works): a) Specify the correct URL to the upload directory in the "optional" field just below the custom image path field. b) There's a new wp-includes/functions.php which will eliminate the issue. Download it and replace your existing wp-includes/functions.php file with it. Je me disais bien qu'il y avait un truc de pété.