delphi POST网页的时候提示“invalid argument to date encode”异常

delphi POST网页的时候提示“invalid argument to date encode”错误！
delphi POST网页的时候提示“invalid argument to date encode”错误！大家帮忙看看

下面这个是delphi的函数

Delphi(Pascal) code

function  TForm1.httpPost(postUrl:string;Params:TStrings):string;var  idhtp1:   TIdHTTP;begin  idhtp1:=   TidHTTp.create(self);  idhtp1.AllowCookies:=True;  //idhtp1.HTTPOptions:=[hoForceEncodeParams];  idhtp1.ProtocolVersion:=pv1_1;  idhtp1.Request.ContentType:='application/x-www-form-urlencoded';  idhtp1.Request.CacheControl:='no-cache';  idhtp1.Request.UserAgent:='Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN; rv:1.9.0.1) Gecko/2008070208 Firefox/3.0.1';  idhtp1.Request.Accept:='text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8';  idhtp1.Request.AcceptEncoding:='Accept-Encoding=gzip,deflate';  idhtp1.Request.AcceptCharSet:='Accept-Charset=gb2312,utf-8;q=0.7,*;q=0.7';  idhtp1.Request.Connection:='keep-alive';  try    result := idhtp1.Post(postUrl,Params);  //运行到这句的时候报错，报错后点击确定，再按下F9又正常返回了！！快疯了！汗！！！大家帮帮忙！  except    Result := 'error';  end;end;快疯了！汗！！！大家帮帮忙！