WM_COPYDATA 进程间通信 传结构体失败.解决方案

WM_COPYDATA 进程间通信 传结构体失败...
a.exe代码：

typedef struct backupinfo  
{
  String sign;
  String backuppath;
}BackupInfo;

void __fastcall TForm1::btn1Click(TObject *Sender)
{
  HWND hWnd = FindWindow("TForm1","Form2");
  if(hWnd)
  {
   
  BackupInfo *backup = new BackupInfo() ;
  backup->sign = "access";
  backup->backuppath = "ddd";

  COPYDATASTRUCT cds;
  cds.dwData = 0 ;
  cds.cbData = sizeof(BackupInfo);
  cds.lpData = (PVOID)backup;
  SendMessage(hWnd,WM_COPYDATA,NULL,(LPARAM)&cds);

  }
}

b.exe代码：

typedef struct backupinfo  
{
  String sign;
  String backuppath;
}BackupInfo;

void __fastcall TForm1::WndProc(Messages::TMessage &Message)
{
  switch (Message.Msg)
  {
case WM_COPYDATA:
{

COPYDATASTRUCT *cds;
cds = (COPYDATASTRUCT*)Message.LParam;
BackupInfo * backup = (BackupInfo*)(cds->lpData);
String sign = backup->sign;

  ....  
  break;
  }
  }
TForm::WndProc(Message);
}

不知道为什么b.exe程序backup结构体接收的数据总是为空...
我a.exe明明给结构体赋值了的

请哪位大哥帮帮忙，我想了一上午都不知道怎么回事，怎么改正？？？

[解决办法]
好像毛毛回答过你这个问题啊，WM_COPYDATA传输的数据，不要用String类型，改成char数组。