Adobe Reader Could not Open Report Output PDF


Hi I am Using a Business Function B0500725 Email Merge Letter To Send Email with Report Output PDF Attachment, Its Working Fine But When I Downloaded PDF from mail and Trying to open its Showing An Error Adobe Reader Could not Open an Email Attachment wasn't correctly Decoded.
Please Help me
Possible causes..
1) Some process is still holding your PDF. Use Un-locker tool to see if the file is hooked to some other process.
2) The file is empty.