Software based input panel (soft keyboard on WinCE 4.0) .NET programming

Below is the code I have written to test showing the soft keyboard and then to hide it when done "typing" in the text box.  However I get an error in the code when running on the device on this line "Showkeyboard = SipShowIM(1)".  Thanks for the help.

Public Class test
    Inherits System.Windows.Forms.Form
    Friend WithEvents Button1 As System.Windows.Forms.Button
    Friend WithEvents Button2 As System.Windows.Forms.Button
    Declare Function SipShowIM Lib "coredll" (ByVal flags As Long) As Long

#Region " Windows Form Designer generated code "

    Public Sub New()
        MyBase.New()

        'This call is required by the Windows Form Designer.
        InitializeComponent()

        'Add any initialization after the InitializeComponent() call

    End Sub

    Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
        MyBase.Dispose(disposing)
    End Sub

    'NOTE: The following procedure is required by the Windows Form Designer
    'It can be modified using the Windows Form Designer.  
    'Do not modify it using the code editor.
    Friend WithEvents TextBox1 As System.Windows.Forms.TextBox
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        Me.Button1 = New System.Windows.Forms.Button
        Me.Button2 = New System.Windows.Forms.Button
        Me.TextBox1 = New System.Windows.Forms.TextBox
        '
        'Button1
        '
        Me.Button1.Location = New System.Drawing.Point(32, 56)
        Me.Button1.Size = New System.Drawing.Size(64, 24)
        Me.Button1.Text = "Keybd on"
        '
        'Button2
        '
        Me.Button2.Location = New System.Drawing.Point(32, 88)
        Me.Button2.Size = New System.Drawing.Size(64, 24)
        Me.Button2.Text = "Keybd off"
        '
        'TextBox1
        '
        Me.TextBox1.Location = New System.Drawing.Point(16, 16)
        Me.TextBox1.Size = New System.Drawing.Size(96, 22)
        Me.TextBox1.Text = ""
        '
        'test
        '
        Me.ClientSize = New System.Drawing.Size(244, 274)
        Me.Controls.Add(Me.TextBox1)
        Me.Controls.Add(Me.Button2)
        Me.Controls.Add(Me.Button1)
        Me.Text = "test"

    End Sub

#End Region

    Private Function Showkeyboard() As Long
        Showkeyboard = SipShowIM(1)
    End Function

    Private Function Hidekeyboard() As Long
        Hidekeyboard = SipShowIM(0)
    End Function
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Showkeyboard()
    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        Hidekeyboard()
    End Sub
End Class