A bug was found in the phpBB 3.x series that would not allow bitmaps to be properly attached. A temporary fix has been applied until the next version of phpBB (3.0.2) is released in which the changes will be merged/replaced. If you have had problems uploading bitmaps in the past due to errors or no image after posting, simply edit your post, delete the attachment and reattach it. I have tested with one of Krum's attachments and everything seems to be working fine. If you encounter any errors with attaching bitmaps, you can either post it here or head over to the phpBB bug tracker and post it there.