请问：如下 为什么？

bfaomei

FreeOnTerminate := True;
     lExcelToTable:=TExcelToTable.Create(nil);
     try
         lExcelToTable.FileName := FORMDOC1.input_config_dt.DataSet.FieldByName('file_name').AsString;
         bookname := FORMDOC1.input_config_dt.DataSet.FieldByName('sheet_name').AsString;//运行到该处报错误.

bfaomei

procedure TMyThread.Execute;
var
   lExcelToTable:TExcelToTable;
   bookname , lmsg,megstr: string;
begin
    FreeOnTerminate := True;
     lExcelToTable:=TExcelToTable.Create(nil);
     try
         lExcelToTable.FileName := FORMDOC1.input_config_dt.DataSet.FieldByName('file_name').AsString;//这里出错



//创建线程;
type
  TMyThread = class(TThread)
  private
    FORMDOC1:TBUSS_CUST_BALANCE_FORMDOC;
  public
    procedure Execute; override;
    property FormDoc: TBUSS_CUST_BALANCE_FORMDOC read FORMDOC1 write FORMDOC1;
  end;



//引用线程
procedure TBUSS_CUST_BALANCE_FORMDOC.Button_inputClick(Sender: TObject);
begin
TMyThread.Create(False);   
end;

zfang

报什么错呢。