Descrescendo difficulty

[rif]

          \context Voice = VA { \stemDown
            <gis2 e b> <fis8 dis b^\accent> r b a 
            <gis2 b,> <fis cis>
          }

Compiles fine.  I want a decrescendo to start on the first chord,
finish on the second chord, but anywhere I put it I seem to get a
parse error. For instance, 

          \context Voice = VA { \stemDown
            \> <gis2 e b> <fis8 dis b^\accent> \! r b a 
            <gis2 b,> <fis cis>
          }

generates a parse error when it hits the \>.  I have tried putting the
start and end marks in all kinds of places.  How do I get this to
work?  Does white space matter?  In the examples in the manual, the
starts and ends of (de)crescendos are marked directly before or after
the note.  In another context, that seemed not to be impotant:

          < \context Voice = VA { \stemUp
            fis8 gis a dis, e4 b
            \< [gis'8 e\staccato] [b' gis\staccato] \! cis4-\mf b8 a 
            }

does the right thing.

What am I missing?

rif