Tilde causes error message: "unrecognized string, not in text script or \lyricmode"

[Eyolf Østrem]

If I try to run the following (either directly or as part of a score):

\relative c' {
\key e \minor
\time 4/4

r4 r8 e8 e fis g4 fis fis8 fis fis e dis e ~ e4 r8
e8 e fis g4 a a8 a a g a b~ b4 r8
b b b b4 c c8 c c b a b~ b4 r8
b8 b a g4  fis fis8 fis fis e dis e ~ e4 r8
}

I get the error message: "unrecognized string, not in text script or 
\lyricmode" at the tildes in the first and last line. The "e"s after the 
tildes do not get written out. The two "b~" work as expected, though, 
even though everything but the pitches is the same as in the first line.
If I remove the tildes, everything works - except that I don't get the ties.

I'm running v. 2.18.2 under Arch Linux.

Eyolf