ASCII CHECK - change value in primary key

Hi,

I've some trouble in checking ASCII with 10 or 13 in database.
When I find out there are data with ASCII 13 or 10, i will detele it then replace back to original data.
it seems work in regular fields except primary key fields.
My thought was delete the field value before I insert new value into it.
I can't use RENAME, it will occur another modify problem.
Then here's the problem that I met, not sure if my code are correct or not, need your help.When the Fields are Key Column, I will DELETE it first then INSERT the new value to Field
but it shows me a massage like (I've searched the table 'Item') : The Item does not exist,
Identification fields and values: No.='A-I000001'

But If I didn't delete it first , it will show me : the Item already exists.

What should I do to change the primary key value?

Really need your help.

Windows.OPEN(Text000+
             Text001+
             Text002);
IF g_intTableNo >0 THEN
  g_recField.SETRANGE(TableNo,g_intTableNo);

IF g_recField.FIND('-') THEN
  IF g_recField.Enabled = TRUE THEN
  REPEAT
    CLEAR(g_rrfRecordRef);
    CLEAR(g_krfKeyRecordRef);
    g_rrfRecordRef.OPEN(g_recField.TableNo);
    g_krfKeyRecordRef.OPEN(g_recField.TableNo);
    Windows.UPDATE(1,g_recField.TableName);  //
    g_krfKeyRef := g_rrfRecordRef.KEYINDEX(1);
    g_intKeyCount := g_krfKeyRef.FIELDCOUNT;
    FOR i:= 1 TO g_intKeyCount DO BEGIN
      g_frfFieldIndex[i] := g_krfKeyRef.FIELDINDEX(i);
    END;
    IF g_rrfRecordRef.FIND('-') THEN BEGIN
      g_frfFieldRef := g_rrfRecordRef.FIELD(g_recField."No.");
      Windows.UPDATE(2,g_recField.FieldName);                     //
      IF (g_recField.Type = g_recField.Type::Code) OR
         (g_recField.Type = g_recField.Type::Text) THEN
        REPEAT
          CLEAR(l_txtNewValue);
          CLEAR(l_txtOldValue);
          CLEAR(l_txtKeyValue);
          CLEAR(l_booKeyColumn);
          l_txtOldValue := g_frfFieldRef.VALUE;
          Windows.UPDATE(3,l_txtOldValue); //
          FOR i:= 1 TO STRLEN(l_txtOldValue) DO BEGIN
            cSTR := l_txtOldValue[i];
            IF (cSTR <> 13) AND (cSTR <> 10) THEN
              l_txtNewValue += FORMAT(l_txtOldValue[i]);
          END;
          g_txtNewValue := l_txtNewValue;
          FOR i:= 1 TO g_intKeyCount DO BEGIN
            IF g_frfFieldRef.NAME = g_frfFieldIndex[i].NAME THEN BEGIN
              l_intKeyIndex := i;
              l_booKeyColumn := TRUE;
              g_frfFieldIndex[i].VALUE := l_txtNewValue

            END;
            IF l_booKeyColumn THEN BEGIN
              //f_booRenameKeyField(g_intKeyCount);
              f_inserKeyField(g_intKeyCount);
            END ELSE BEGIN
              g_frfFieldRef.VALUE := l_txtNewValue;
                //IF NOT g_rrfRecordRef.MODIFY THEN
               // ERROR('Modify failure Column: %1 Value: %2',g_frfFieldRef.NAME,l_txtNewValue);
            END;
           END;
        UNTIL g_rrfRecordRef.NEXT = 0;
      g_rrfRecordRef.CLOSE;
    END;
  UNTIL g_recField.NEXT = 0;

MESSAGE('Finished!');
Windows.CLOSE;
---------------------------------------------------
[Function:f_booRenameKeyField(p_intKeyCount : Integer)]

CASE p_intKeyCount OF
  1: 
   BEGIN
      g_rrfRecordRef.DELETE;
      g_frfFieldRef.VALUE := g_frfFieldIndex[1].VALUE;
      g_rrfRecordRef.INSERT;

   END;
END;