.net security exception

Question

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.net security exception

I am using OpenFileDialog class to browse a file in window application using c#. It is giving the security exception as below.

Request for the permission of type 'System.Security.Permissions.FileIOPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed.

My code is

    OpenFileDialog fdlg = new OpenFileDialog(); 
    fdlg.Title = "C# Corner Open File Dialog"; 
    fdlg.InitialDirectory = @"c:\"; 
    fdlg.Filter = "All files (*.*)|*.*|All files (*.*)|*.*"; 
    fdlg.FilterIndex = 2; 
    fdlg.RestoreDirectory = true; 
    if (fdlg.ShowDialog() == DialogResult.OK) 
    { 
        txtpath.Text = fdlg.FileName; 
    } 

I am not getting the problem. please help.