TWinHTTP控件以multipart/form-data POST方法上传问题

在BCB里我用TWinHTTP控件以multipart/form-data POST方法上传遇到问题了，代码如下：
void __fastcall TForm1::UploadBtnClick(TObject *Sender)
{
WinHTTP1->URL="http://127.0.0.1:8080/vsms/upload.do";
WinHTTP1->Upload(2);
WinHTTP1->Read();
}
//---------------------------------------------------------------------------
void __fastcall TForm1::WinHTTP1UploadFieldRequest(TObject *Sender,
WORD FileIndex, TMemoryStream *UploadStream, AnsiString &FieldName,
AnsiString &FileName)
{
if(FileIndex==0) // first 普通
{
FieldName="name";
UploadStream->Write(edUsername->Text.c_str(),edUsername->Text.Length()) ;
}
else if(FileIndex==1) // first file
{
FieldName="file";
FileName="c:\\1.text";
UploadStream->LoadFromFile(FileName);
}
}
//---------------------------------------------------------------------------
小弟本是想把一文件上传到网页上，（BOSS要偶用BCB写，小弟新来的，能力有限）请各位大侠指点。小弟先谢了！