A hint is missing in step two, to send an encrypted message we have to be logged in using our memo key. it was a bit confusing when I tried, the error just said: missing memo key.
getting the memo key wasn't that easy either with the show private key in front of memo key missing when I'm logged in with my posting key. I had to login with my master key first for that to show.
the rest was straight forward, hopefully you're still doing this. ;)