unable to attach file

i"m trying to upload a zine in PDF format, but am unable to upload the file. i click on the "attach" button, and it claims to be uploading for about 45 seconds, and then nothing. file attachments goes back to being blank.
anyone have any ideas?

7 mb upload limit

There is a 7 mb upload limit on this site.

You can also use the "reduce file size" option in acrobat.