Well now you know then. A grep (or google) will show you what kind of payments Bitcoin can do. Public key and public key hash are the two basic types, then there's stuff like script hash which came later, and tomorrow we'll have witness script hash too.
lol, i did google it before i wrote that thing, and also reading the wiki about transaction types there was no mention about p2pk, so my first guess was that you made a simple mistake.
seeing your new comment i dug deeper and found it finally. so thanks i learned a new thing today