error vb6 postmessage usage

Trying to get some calls running in VB6 to use Postmessage  Function
This is a call to the functions in a program wich now i can now only use bij shelling to commandline ,
like   Shell "J:\VIRT_KEYBORD\MOVETOPKB  ", vbHide
Utillity from  https://hot-virtual-keyboard.com/

According their on-site manal  should be possible to do like this


Const WM_CSKEYBOARD = &H400 + 192
Const WM_CSKEYBOARDMOVE = &H400 + 193
Const WM_CSKEYBOARDRESIZE = &H400 + 197
 
Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Integer
Private Declare Function PostMessage Lib "user32" Alias "PostMessageA" (ByVal hWnd As Integer, ByVal wMsg As Integer, ByVal wParam As Integer, _
         ByVal lParam As Integer) As Integer



    'Move Hot Virtual Keyboard in Visual Basic; Move it first then show it    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) ' Handles Button3.Click
        Dim hWnd As Integer
        hWnd = FindWindow("TFirstForm", "hvkFirstForm")
        PostMessage(hWnd, WM_CSKEYBOARDMOVE, 200, 200)
        PostMessage(hWnd, WM_CSKEYBOARD, 1, 0)
    End Sub

But calls to postmessga gives in Editor red syntax status
Support desk from supplier could not help me out on this

please see the attachd file from program listing and response helpdesk wich does not sove my problem

Thanks for help