convert packed to alpha

Hi, i have some problems with this code.

I've tested it with different numbers, (3617900 for example)
and it works fine.

In some cases i've got wrong results.
For Example:
hexstring = hex value of 3494402,  5240211
alphastring = 3494002,  5200211

Hexstring contains the hex value from a packed field (fieldxyz  9p 0).
What's wrong ??????????

The code looks like this

d universal_ds e ds     extname(filexyz)
        ......
d universal         s         500a
        .....
d hexstring     s       500a                    (hexstring contains the hex value from a packed number)
d alphastring   s               500a    inz     (that's the result)
d l                     s                   3p 0        inz             (length oh hexstring)
            
d                    ds                             
d num                             30p 0            
d char16                         16     overlay(num)
        .......
c                   eval      universal = universal_ds
c                   eval      hexstring = %subst(universal:1:5)         (pos 1-5 = packed field 9p 0)
        .......
c                   eval      l = %len(hexstring)
c                   evalr     char16 = %subst(hexstring:1:l)
        .......                                                           
c     ' ':x'00'     xlate     char16        char16         
c                   eval      alphastring = %char(num) 
        .......