A problem with replacing letters

Hello,

I'm working on a Hungarian stemmer and I have a problem I haven't been 
able to solve. The code is added below.  I have a routine called 
v_ending which replaces  "a acute" and "e acute" by "a" and "e".  If I 
simply delete them it works but when I actually try replacing instead of 
an "a" I get an "a acute".
For instance if I test it on the word  "hagyásában" I ought to get 
"hagyása" (with ban removed and a acute replaced) but I get "hagyásá". 
Similar things happen with a word like  "kimenetelében".  I suspect I am 
missing something simple but I just can't figure out what goes wrong.

Thank you

Anna Tordai

**************************

// Hungarian stemmer.

routines (
          mark_regions
      v_ending
      R1
      R2
          case
)

externals ( stem )

integers ( p1 p2 )
groupings ( v )

stringescapes {}

/* special characters (in ISO Latin I) */

stringdef a'    hex 'E1'     // a-acute
stringdef e'    hex 'E9'    //e-acute   
stringdef i'    hex 'ED'    //i-acute
stringdef o'    hex 'F3'    //o-acute
stringdef o"    hex 'F6'    //o-umlaut
stringdef oq    hex 'F5'    //o-double acute 
stringdef u'    hex 'FA'    //u-acute
stringdef u"    hex 'FC'    //u-umlaut
stringdef uq    hex 'FB'    //u-double acute


//vowels
define v 'aeiou{a'}{e'}{i'}{o'}{o"}{oq}{u'}{u"}{uq}'


define mark_regions as (

   $p1 = limit
   $p2 = limit

   (gopast v  (test substring among('cs' 'gy' 'sz' 'ty') setmark p1)) or
   (goto v gopast non-v setmark p1)
   goto v  gopast non-v  setmark p2
)

backwardmode (

   define R1 as $p1 <= cursor   
   define R2 as $p2 <= cursor
  
   define v_ending as (
       [substring] among(
       '{a'}' (<- 'a')
       '{e'}' (<- 'e')
   )
   )

   define case as (
     [substring] among(
           'ban'     //inessive           
       'ben'    //inessive
       )
    delete
   v_ending
   )
)

define stem as (
   do mark_regions
   backwards (
       do case
   )
)