关于delphi xe5 重载的疑惑

Question

1.我有一父类，方法声明如下，实现忽略
protected
     function BeginTransaction:ITransaction;overload;
     function BeginTransaction(contextID:String):ITransaction;overload;
     function BeginTranscation(contextID:String;isolationLevel:TIsolationLevel):ITransaction;overload;
     function BeginTransaction(isolationLevel:TIsolationLevel):ITransaction;overload;
     procedure Commit;
     procedure Rollback;
     procedure Synchronize(trans:ITransaction);子类集成与该父类，声明如下
TObjectBLL = class(TBusiness)问题，在子类方法中调用BeginTransaction（没有输入参数的那个方法）,只有BeginTranscation(contextID:String;isolationLevel:TIsolationLevel)能够调用，其它重载方法调用时全部编译不通过，提示[dcc32 Error] Business.pas(100): E2250 There is no overloaded version of 'BeginTranscation' that can be called with these arguments
我到底问题出在那里？请各位大神帮忙解答!!
调用方法如下
function TObjectBLL.Insert(entity: TJSONValue; AutoPK:Boolean): Boolean;
var
  dal:TObjectDAL;
  tran:ITransaction;
begin
  dal := TObjectDAL.Create;
  try    tran:= BeginTranscation();
  finally
    dal.Free;
    dal:=nil;
  end;
end;overload重载delphi xe5

Answer 1

     function BeginTransaction:ITransaction;overload;
     function BeginTransaction(contextID:String):ITransaction;overload;
     function BeginTranscation(contextID:String;isolationLevel:TIsolationLevel):ITransaction;overload;
     function BeginTransaction(isolationLevel:TIsolationLevel):ITransaction;overload;