Filling a listsore real time

["ldries46" <bertus.dries@planet.nl>]

In my program I want a combobox with a liststore that is every time the 
dialog in which it is called has a different  number of of iters and another 
value within the iter. In this case the iters are from an array of 
characters.
It looks like the Routine Set_Value  or Set_Char is not correct working 
because I checked the input for Set_Char gchar(ch) gives me the correct 
Character. append also works correct, I get the correct number of items but 
the items should be 1, 2, 3, 4, 5, 6, 7, 8, 9 and they are 0, 0, 0, 0, 0, 0, 
0, 0, 0, 0

n1 := 0;
for nn in 1 .. max loop
   if not Grid(x_vak, y_vak).impossible(n1) then
      ch := CHARACTER'Val(Symbols(n1 ,Set));
      Set_Char(G_char, gchar(ch));
      append(CH_List, CH_Iter);
      Set_Value(CH_List, CH_Iter, 0, G_char);
   end if;
   n1 := n1 + 1;
end loop;

Can anyone tell me what I am doing wrong. The only tutorials I can find who 
are a little bit close to my problem are for c or python.

L. Dries