How do I copy TextBox to Clipboard?

Imported Namespace:
<%@ Import Namespace="System.Windows.Forms.Clipboard" %> Script:
<Script Runat="Server"> Sub CopyToClipboard_Click(sender As Object, e As System.EventArgs)
Clipboard.SetDataObject(TextBox1.SelectedText)
End Sub
</Script> Code:
<form Runat="Server"> <asp:TextBox Width="409" ID="TextBox1" ReadOnly="true" value="Test" Runat="Server"/> <asp:LinkButton Text="(Copy to Clipboard)" ID="lbCopyToClipboard" Runat="server" OnClick="CopyToClipboard_Click" /> </form> Error: Compiler Error Message: BC30451: Name 'Clipboard' is not declared.
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