"programming error"

[C.Flothow]

When trying to prepare an example for this list (concerning the missing 
paragraph  "Ancient and Modern from One Source") I came across the 
following problem:

   \version "2.12.2"

   {\time2/2 \times 1/2{\relative c''{g1 g  \time 3/2 f fis2 g1 a2 a b 
c4 a~a g2 g4 f2  \time 2/2 e1 }}}


produces a "programming error" and gives two staffs for reasons unknown 
to me .

Chris