That is normal behavior. To save bandwidth, the attachment is not included in the reply, but the file name is included in the returned text as a reminder there was an attachment. If you want to include the attachment in the reply you will have to re-attach it to the reply from the copy you saved on your computer. To save the attachment, either drag it to your desktop or some other folder, before you reply to the message, or archive the original message. Unless the attachment has been saved, it is deleted when the original message is deleted.
