adoquery与access 连接问题

为什么我在用adoquery连接的时候,老说我没有连接上那
我的程序是:ASql:='select * from table1 ';
ASql:= ASql + ' order by date_begin desc ';

try
with aDOQuery1 do
begin
Close;
ConnectionString:= DataModule1.TabCon;
Sql.Clear;
Sql.Add(ASql);
Open;
end;
finally
cxButton5.Enabled:= True;
end;

而且，我在Data_Module中定义了路径的
AppPath :=ExtractFilePath(Application.ExeName); //获得当前执行程序所在的路径
if AppPath[length(AppPath)] <> '\' then
AppPath := AppPath + '\';
TabCon :='FILE NAME='+AppPath+'Tabcon.udl';