Draft Id Not Found
You are trying to send a draft which has been already sent or deleted. When you create a draft in Merge to Draft mode and you send it in Draft to Send mode you cannot send it again. Once a draft is sent it is moved to Sent folder and draft id becomes obsolete. The draft is no more a draft but a sent message.
If you still want to send the same message the only option you have is to reprocess again a row.