XF 2.2 Attachments not uploading



Sorry my forum has been shut for a year now, just on closed and doing nothing, but this week I reopened it and wanted to upload some pdf's for members to be able to download. However, Whenever I go to upload, the green upload bar starts to upload, then finishes before it reaches the end and then its just left with an empty box, which when you click "post" does not show up on the forum.

Anyone have any ideas?