compiler errors - Can't get simple Ada Iterator example to compile -

i'm learning ada , trying simple loop working (using new iterators syntax ada 2012). cannot see what's wrong...

with ada.text_io; use ada.text_io;  procedure arrays   type v array (0 .. 1, 0 .. 2) of natural;   : v := ((10, 20, 30), (400, 500, 600)); begin   e of loop  --  compiler error here!     e := e + 1;   end loop; end arrays; 

my compile command "$ gnatmake -gnaty -gnaty2 -gnat12 arrays" (for pedantic style enforcement , enable 2012 features). compiler error is

arrays.adb:8:14: few subscripts in array reference 

(i'm using gnatmake 4.6 on raspi).

this code pieced john barnes' book "programming in ada 2012" p.120-121. i've trimmed down code as can, that's why doesn't much. far can see, it's effetively identical examples in book.

what doing wrong?