Simple DLL problem

library collexconv;

uses
  ShareMem,
  SysUtils,
  Classes;

 var
 StrNum: TStringList;

{$R *.res}

Function ExtNum(S: String): String; stdcall;
begin
StrNum := TStringList.Create;
StrNum.Delimiter := ',';
StrNum.DelimitedText := S;
StrNum.Free;
Result := StrNum.Strings[0];
Result := copy(Result,5,7);
end;

Function DateOfCall (S: String): String; stdcall;
Begin
StrNum := TStringList.Create;
StrNum.Delimiter := ',';
StrNum.DelimitedText := S;
StrNum.Free;
Result := StrNum.Strings[1];
end;
Function SQLDateOfCall (S: String): String; stdcall;
Begin
StrNum := TStringList.Create;
StrNum.Delimiter := ',';
StrNum.DelimitedText := S;
StrNum.Free;
      Result := '20'+copy(StrNum.Strings[1],7,2)+'-'+copy(StrNum.Strings[1],4,2)+'-'+copy(StrNum.Strings[1],1,2);
end;

Function TimeOfCall (S: String): String; stdcall;
Begin
StrNum := TStringList.Create;
StrNum.Delimiter := ',';
StrNum.DelimitedText := S;
StrNum.Free;
Result := copy(StrNum.Strings[2],1,2)+':'+copy(StrNum.Strings[2],3,2)+':'+copy(StrNum.Strings[2],5,2);
end;


exports
ExtNum,DateOfCall, SQLDateOfCAll;
end.

unit importcheck;

interface

uses
  ShareMem, Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

    Function ExtNum (S: String): String; stdcall; external 'collexconv.dll';
    Function DateOfCall (S: String): String; stdcall; external 'collexconv.dll';
    Function SQLDateOfCall (S: String): String; stdcall; external 'collexconv.dll';

type
  TForm1 = class(TForm)
    CdrImportEdit: TEdit;
    CdrButtonOk: TButton;
    Button2: TButton;
    Edit2: TEdit;
    Edit3: TEdit;
    Edit4: TEdit;
    CdrOpenDialog: TOpenDialog;

    procedure Button2Click(Sender: TObject);
    procedure CdrButtonOkClick(Sender: TObject);

  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
    CdrText: Textfile;
  Buffer1: String;

  Exten: String;
  CallDay : String;
  SQLDate : String;



implementation

{$R *.dfm}

procedure TForm1.Button2Click(Sender: TObject);
begin
 if CdrOpenDialog.Execute then
 CdrImportEdit.Text := CdrOpenDialog.FileName;
end;

procedure TForm1.CdrButtonOkClick(Sender: TObject);
begin
   CdrButtonOK.Enabled := False;
    CdrImportEdit.Enabled := False;


    Assignfile(CdrText, CdrImportEdit.Text);
    Reset(CdrText);
    while not EOF(CdrText) do begin
    ReadLn (CdrText, Buffer1);
    end;
    Reset(CdrText);
    Index := 0;

//loop though each line of text
        while not EOF(CdrText) do begin
        ReadLn (CdrText, Buffer1);

                Exten := ExtNum(buffer1);
                CallDay := DateOfCall(buffer1);
                SQLDate := SQLDateofCAll(buffer1);

                edit2.Text := Exten;
                edit3.Text := DateOfCall;
                edit4.Text := SQLDateOfCall;
        end;
end;

end.

Function ExtNum(S: String): String; stdcall;
begin
StrNum := TStringList.Create;
StrNum.Delimiter := ',';
StrNum.DelimitedText := S;
Result := StrNum.Strings[0];
Result := copy(Result,5,7);
StrNum.Free;
end;