Visual Basic 2010 How can I tell if the user stops pressing a key

Hi all
I am using the code below and I just need a way of telling if the user has stopped pressing a key.
Have tried to use Key up  but I can not get it to work? please can you show me how I can do it Thanks

Protected Overrides Function ProcessCmdKey(ByRef msg As Message, ByVal keyData As Keys) As Boolean

           Select keyData
            Case Keys.Down
                key1 = Keys.Down
                If key2 <> key1 Then
                    Call tiltdown1()
                End If
                key2 = key1

            Case Keys.Up
                key1 = Keys.Up
                If key2 <> key1 Then
                    Call tiltup1()
                End If
                key2 = key1

            Case Keys.Right
                key1 = Keys.Right
                If key2 <> key1 Then
                    Call Panright1()
                End If
                key2 = key1

            Case Keys.Left
                key1 = Keys.Left
                If key2 <> key1 Then
                    Call Panleft1()
                End If
                key2 = key1

            Case Keys.M
                key1 = Keys.M
                If key2 <> key1 Then
                    Call zoomout1()
                End If
                key2 = key1

            Case Keys.N
                key1 = Keys.N
                If key2 <> key1 Then
                    Call zoomin1()
                End If
                key2 = key1

            Case Keys.S
                key1 = Keys.S
                If key2 <> key1 Then
                    Call allstop1()
                End If
                key2 = key1

        End Select
        Return temp(0)

    End Function

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