Unix (In)Security

[boyle at ANL-MCS.ARPA]

Derek Andrew at U of Saskatchewan says:

    Another comment made by the speaker was that there have been 5 attempts
    at generating secure Unix kernels.  All attempts have not been successful
    and 4 have been aborted.  

The second sentence means "there exists an attempt that has not been
successful".  Does that mean that some attempts were successful?  Or
did he mean to say "No attempt has been successful"?
			Jim Boyle