changing time signature

[Jean-marc LEGRAND]

Hi list, ands thanks again for your support !

My new problem is with time signature changes. Here's my .ly, with lily2.0.1 on 
XP :

\version "2.0.1"
\score      {
      \notes {
            \time 2/2
            {
a'1
a1
\once \property Score.timing = ##f
a\breve
\bar "||"
\time 3/4
a2.
a2.
\bar "|."
            }
            }
\paper {}
\header {}
}

The pb is that after the \breve and \bar "||", it seems that "automatic 
barnlining" is off. I have
next 2 dotted half notes without barline between.

How is this ?