写内存写错了

procedure TForm1.Button1Click(Sender: TObject);
var
pItem: TLVItem;
Buff: PChar;
PID,PRC: THandle;
R: Cardinal;
hwnd:tHandle;
begin
        hwnd:= FindWindow('#32770','Windows 任务管理器');
        hwnd:= FindWindowEx(hwnd,0,'#32770',0);
        hwnd:= FindWindowEx(hwnd,0,'SysListView32',0);

  GetWindowThreadProcessId(hwnd, @PID);
  PRC := OpenProcess(PROCESS_VM_OPERATION or PROCESS_VM_READ or
  PROCESS_VM_WRITE, False, PID);
  Buff := VirtualAllocEx(PRC, nil, 4096, MEM_RESERVE or MEM_COMMIT,
  PAGE_READWRITE);
  ZeroMemory(@pItem,SizeOf(pItem));
  with pItem do
  begin
    mask := LVIF_TEXT;
    pszText := PChar(integer(Buff) + SizeOf(pItem) * 4);
    cchTextMax := Length(Edit1.Text)+1;
  end;
  WriteProcessMemory(PRC, Buff, @pItem, Sizeof(pItem), R);
  WriteProcessMemory(PRC, PChar(integer(Buff) + SizeOf(pItem) * 4),
  PChar(Edit1.Text), Length(Edit1.Text)+1, R);
  SendMessage(hwnd,LVM_INSERTITEM,0,LongInt(Buff));
  VirtualFreeEx(PRC, Buff, 0, MEM_RELEASE);
  CloseHandle(PRC);

end;

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