VB 发送消息到指定程序

Private Sub Command1_Click()
Dim s As String
Dim FT_hWnd As Long
Dim ID_Control_hWnd As Long
s = Text1.Text
FT_hWnd = FindWindow(vbNullString, "Form1")
If FT_hWnd = 0 Then
MsgBox "False", vbInformation, "Title"
End If
ID_Control_hWnd = GetDlgItem(FT_hWnd, ThunderRT6TextBox2)
SendMessage ID_Control_hWnd, WM_SETTEXT, 0, ByVal s
End Sub

ThunderRT6TextBox2这个是控件类名是ThunderRT6TextBox接口是2的TEXT控件

为什么接收不到啊我要发送到“Form1”的第二个text控件，在线等高手解答

D_Control_hWnd = GetDlgItem(FT_hWnd, "ThunderRT6TextBox2")