Tagline stuck to the default one

[Elmo Todurov]

In my opinion, I'm doing everything correctly. However, the
tagline is the default.
The code is here. I'm sure it's correct.
\paper { printallheaders = ##t }
\layout {}
\version "2.9.7"
\score {
  \new Staff {
    c4 c4
  }
  \header {
    title = "tit"
    tagline = "tag"
  }
}
The title shows correctly, but the tagline is the default
"Music engraving ..." I hacked the default title in the
distribution and got my scores right, but that's not a solution.
What's wrong?