Не отправляется сообщение окну SendMessage (winApi)

Const WM_COPYDATA As Integer = &H4A
<DllImport("user32.dll")> _
    Public Shared Function FindWindow(lpClassName As String, lpWindowName As String) As Integer
    End Function
    <DllImport("user32.dll", SetLastError:=True, CharSet:=CharSet.Auto)>
    Private Shared Function SendMessage(ByVal hWnd As IntPtr, ByVal Msg As UInteger, ByVal wParam As IntPtr, ByVal lParam As IntPtr) As IntPtr
    End Function
 
Private Shared Sub SendHWND(hw As Integer, Name As String)
Dim ptr As IntPtr = Marshal.StringToHGlobalAnsi("test")
        SendMessage(hw, WM_COPYDATA, IntPtr.Zero, ptr)
    End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim handle As IntPtr = FindWindow(Nothing, "CDPReceiver")
        Debug.Print(handle)
        If handle <> IntPtr.Zero Then
            SendHWND(handle, "hello")
        End If
    End Sub

Const WM_COPYDATA As Integer = &H4A
    Protected Overrides Sub WndProc(ByRef m As Message)
        Select Case m.Msg
            Case WM_COPYDATA
                   MessageBox.Show("Hey!")
        End Select
        MyBase.WndProc(m)
    End Sub

Imports System.Runtime.InteropServices
 
Public Class Form1
    Const WM_COPYDATA As Integer = &H4A
    Const WM_NULL As Integer = 0
    Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Integer
    Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Integer, ByVal wMsg As Integer, ByVal wParam As Integer, ByVal lParam As IntPtr) As Integer
 
    Private Shared Sub SendHWND(ByVal hw As Integer, ByVal Name As String)
        Dim ptr As IntPtr = Marshal.StringToHGlobalAnsi(Name)
        SendMessage(hw, WM_NULL, 0, ptr)
    End Sub
 
    Private Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button1.Click
        Dim handle As Integer = FindWindow(Nothing, "CDPReceiver")
        If handle <> 0 Then SendHWND(handle, "Hello, world! ") Else MsgBox("handle = 0")
    End Sub
 
End Class

Public Class Form1
    Const WM_COPYDATA As Integer = &H4A
    Const WM_NULL As Integer = 0
    Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message)
        If CInt(m.Msg) = WM_Null Then
            MsgBox(m.Msg)
        End If
        MyBase.WndProc(m)
    End Sub
 
End Class