find random karakter

I oncreate:
Randomize;

....
var
i:integer;
begin
i := Random(length(edit1.text));
edit1.text[I] := uppercase(edit1.text[I])
end;

sorry sådan skulle det være:

procedure TForm1.FormCreate(Sender: TObject);
begin
Randomize;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
i:integer;
str:string;
begin
str := edit1.text;
i := Random(length(str)-1);
str[I] := Uppercase(str[I])[1];
edit1.text := str;
end;

virker perfekt - takker :)