tenuto symbol printed as weired mezzo-staccato

[Peter Chubb]

Hi,
        I want a tenuto -- I get an upside-down mezzo-staccato (dot
above line)

\score {
    {
    \notes\relative c'' { c1-_ }
    }
}

--
Dr Peter Chubb                              address@hidden
You are lost in a maze of BitKeeper repositories, all almost the same.