Switch Case, a constant value is expected

The switch doesn't work, any help is welcome


using System;

using System.Windows.Forms;

using System.IO;

using Valor.Core;

using Valor.Core.Plugins;

using Valor.Utils;

using Valor.Utils.Templates;

using Valor.Boms;

using Valor.Assemblies;

using Valor.Boards;

namespace nsOFD

{

    public class Script

    {

        [InitLibrary("Opportunities for Defect", "Generate OFD Report")]

        public static void InitLibrary()

        {

        }

       

        [Script("Report oveview OFD", ScriptCategory.Misc)]

        public static ExecutionResult OFD(string[] Args)

        {

            ExecutionResult functionReturnValue = default(ExecutionResult);

            Board board = default(Board);

            Bom bom = default(Bom);

            Pca pca = default(Pca);

            //Enter customer name that will appear in sheet headers

            string custName = "Test";

            //Find out what the active object is

            switch (true)

            {

                case ValorApplication.ActiveObject is Bom:

                    bom = (Bom)ValorApplication.ActiveObject;

                    pca = (Pca)bom.Pca;

                    board = pca.Board;

                    if (board == null)

                    {

                        MessageBox.Show("The selected PCA does not have a Board attached!","No PCA", MessageBoxButtons.OKCancel, MessageBoxIcon.Error);

                        return functionReturnValue;

                    }

                    break;

                case ValorApplication.ActiveObject is Pca:

                    pca = (Pca)ValorApplication.ActiveObject;

                    board = pca.Board;

                    bom = (Bom)pca.Bom;

                    if (bom == null)

                    {

                        MessageBox.Show("The selected PCA does not have a Bom attached!", "No BOM", MessageBoxButtons.OKCancel, MessageBoxIcon.Error);

                        return functionReturnValue;

                    }

                    if (board == null)

                    {

                        MessageBox.Show("The selected PCA does not have a Board attached!", "No Board", MessageBoxButtons.OKCancel, MessageBoxIcon.Error);

                        return functionReturnValue;

                    }

                    break;

                default:

                    MessageBox.Show("Please select a PCA!", "Select PCA", MessageBoxButtons.OKCancel, MessageBoxIcon.Error);

                    return functionReturnValue;

            }

        }

    }

}