The first MFT is a critical sector. There are actually two such sectors, and both are searched for before this error message is displayed. The way to recover from this problem is as below
In Recover function, the following options must be selected, enabled
The program will then scan the whole disk for MFTs. It then does two stages of recovery which may look a bit odd if the first MFT is missing. The first stage is to try and recover all files that exist in the full MFT file - which in this case may not exist as a file. The second stage is then to recover all files relating to an MFT. Problems that can exist with this mode is that occassionally directory paths can not be resolved fully, so files may appear in invalid, or incorrect directories. CnW are working on this problem.