I downloaded Tails 1.8, along with its signature file, installed Gpg4win as instructed and followed the instructions to verify the signature. (Tried my best to understand the considerably confusing guide)
This is what I got
Signed on 2015-12-15 10:13 with unknown certificate 0xBA2C222F44AC00ED9899389398FEC6BC752A3DB6. The validity of the signature cannot be verified.
What does that mean? Did I do it wrong? Should I not use this iso?