Trouble setting cooperative level [SharpDX]

[Jayme65]

Hi, I'm using SharpDX for DirectInput joystick management...and I can't resolve the problem I get while setting cooperative level

Imports SharpDX
Imports SharpDX.DirectInput
Imports System.Windows.Interop

Class MainWindow
Private Sub Window_Loaded(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs) Handles MyBase.Loaded
MainForJoystick()
End Sub
'
Private Shared Sub MainForJoystick()
' Initialize DirectInput
Dim directInput As New DirectInput

    ' Find a Joystick Guid
    Dim joystickGuid = Guid.Empty

    For Each deviceInstance As DeviceInstance In directInput.GetDevices(DeviceType.Gamepad, DeviceEnumerationFlags.AllDevices)
        joystickGuid = deviceInstance.InstanceGuid
    Next

    ' If Gamepad not found, look for a Joystick
    If joystickGuid = Guid.Empty Then
        For Each deviceInstance As DeviceInstance In directInput.GetDevices(DeviceType.Joystick, DeviceEnumerationFlags.AllDevices)
            joystickGuid = deviceInstance.InstanceGuid
        Next
    End If

    ' If Joystick not found, throws an error
    If joystickGuid = Guid.Empty Then
        Debug.Print("No joystick/Gamepad found.")
    End If

    ' Instantiate the joystick
    Dim hwnd As IntPtr = New WindowInteropHelper(Application.Current.MainWindow).EnsureHandle()
    Dim joystick = New Joystick(directInput, joystickGuid)
    joystick.SetCooperativeLevel(hwnd, CooperativeLevel.Foreground)
    Debug.Print("Found Joystick/Gamepad with GUID: {0}", joystickGuid)

    ' Set BufferSize in order to use buffered data.
    joystick.Properties.BufferSize = 128

    ' Acquire the joystick
    joystick.Acquire()

    ' Poll events from joystick
    While True
        joystick.Poll()
        Dim datas = joystick.GetBufferedData()
        For Each state As JoystickUpdate In datas
            Debug.Print(state.ToString)
            ' Example detecting 'Up' button
            If state.Offset = 60 Then
                If state.Value = 128 Then
                    Debug.Print("Up button pressed")
                End If
            End If
        Next
    End While
End Sub

End Class

The problem comes from here: joystick.SetCooperativeLevel(hwnd, CooperativeLevel.Foreground) SharpDX.SharpDXException was unhandled HResult=-2147024809 Message=HRESUL