Title of a multi-movement piece of several ly files

[Imruska]

Hello,

I created a Palestrina Mass score, each movement (Kyrie, Gloria, Credo, 
Sanctus, Benedictus, Agnus I, Agnus II) in an independent file, and I 
tried to create a file (missa.ly) to contain them all, using \include 
"kyrie.ly" \include "gloria.ly" etc.

The header of missa.ly is:

\header {
        title = "Missa Sine nomine"
        composer = "Palestrina"
        tagline = ""
}

whereas the headers of the individual files are

\header
        {
        piece="Kyrie"
        composer=""
        tagline= ""
        }

I copied this from a file my brother did with Lilypond 1.6.5, and it 
worked there.

I'm using 2.5.31 on Linux, and this does not work, I do not get title, 
nor composer, and I get for each movement the piece title of "Agnus Dei 
II", i.e. the piece information of the very last file.

How can this be done? I did not find information about this in the 
manual, either.

Imruska