[RESOLVED] mouse hook problem

[mirrormirror]

i'm using a mouse hook in order to trap mouse clicks as following :

Option Explicit

Public Const WH_MOUSE = 7
Public Const WM_LBUTTONDOWN = 513
Public Const WM_RBUTTONDOWN = 516
Public Const HC_ACTION = 0

Public IsHooked As Boolean

Private Declare Function SetWindowsHookEx Lib "user32" Alias "SetWindowsHookExA" ( _
    ByVal idHook As Long, _
    ByVal lpfn As Long, _
    ByVal hmod As Long, _
    ByVal dwThreadId As Long _
) As Long

Private Declare Function UnhookWindowsHookEx Lib "user32" ( _
    ByVal hHook As Long _
) As Long

Private Declare Function CallNextHookEx Lib "user32" ( _
    ByVal hHook As Long, _
    ByVal nCode As Long, _
    ByVal wParam As Long, _
    lParam As Any _
) As Long

Public hMhook As Long
Public rmouseButtonWasPressed As Boolean
Public Sub SetMouseHook()
    
    If IsHooked = False Then
        hMhook = SetWindowsHookEx(WH_MOUSE, AddressOf MouseHookProc, App.hInstance, 0)
        IsHooked = True
    End If
    
End Sub
Public Sub RemoveMouseHook()
    
    UnhookWindowsHookEx hMhook
    IsHooked = False
    
End Sub
Public Function MouseHookProc(ByVal nCode As Long, ByVal wParam As Long, lParam As Long) As Integer

    If (nCode >= 0 And nCode = HC_ACTION) Then
        If wParam = WM_RBUTTONDOWN And rmouseButtonWasPressed = False Then
            rmouseButtonWasPressed = True
            Form1.Text1.Text = "rmouse"
        Else
            rmouseButtonWasPressed = False
            Form1.Text1.Text = ""
        End If
    End If
    
    MouseHookProc = CallNextHookEx(hMhook, nCode, wParam, lParam)

End Function

it works fine, until i alt-tab to another window and switch back to this, the procedure doesn't get the event any more. anybody knows why ?