Error: Entity Name such as "Show window " is not found in current context

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Linux

WPF

In XYZ.xaml
.........
.........
<Button HorizontalAlignment ="Left" VerticalAlignment="Top" Name="NewFooBtn" Click="MyFunction_Click" ToolTip="NewFoo">NewFoo/Button>
.........
.........

In XYZ.xaml.cs:
[DllImport("user32.dll", CharSet = CharSet.Auto)]
public static extern IntPtr FindWindow(string strClassName, string strWindowName);
[DllImport("user32.dll")]
static extern bool ShowWindow(IntPtr hWnd, SHOW_WINDOW nCmdShow);
[DllImport("user32.dll")]
static extern bool BringWindowToTop(IntPtr hWnd);
....
....
public void MyFunction_Click(object sender, RoutedEventArgs e)
{
IntPtr hndl = FindWindow(null, "MSTK2.0.2");
if (hndl != IntPtr.Zero)
{
ShowWindow(hndl, SHOW_WINDOW.SW_RESTORE);
BringWindowToTop(hndl);
return;
}
}
Error 11 The name 'FindWindow' does not exist in the current context E:\23_01_2012_6PM\23_01_2012_9AM\20_01_2012_9AM\MyProj.xaml.cs 430 31Error
12 The name 'ShowWindow' does not exist in the current context E:\23_01_2012_6PM\23_01_2012_9AM\20_01_2012_9AM\MyProj.xaml.cs 433 21
Error 13 The name 'SHOW_WINDOW' does not exist in the current context
E:\23_01_2012_6PM\23_01_2012_9AM\20_01_2012_9AM\MyProj.xaml. 433 38
Error 14 The name 'BringWindowToTop' does not exist in the current context
E:\23_01_2012_6PM\23_01_2012_9AM\20_01_2012_9AM\MyProj.xaml.cs 434 21

How can I resolve the above error., I am using WPF as development(IDE),
Any Help in resolving above would be much appreciable.
Also, using VS2008
on Win 7 o/s.
With Regards,
Samanth_90