Wix v3 Installer: pass parameters to custom action

Question

I am working on a rather large size wix v3 installer. I am required to add registry entries based on various conditions. For that, I will have to write elaborate logic in the C# side. I will do that in custom action. To test my framework, I created a simple custom action and am trying to just test passing parameters from the wxs file to the custom action (C#) side. No matter what I do, when I check the arguments on the custom action side, the arguments are just not there. The related part of the wxs file and the custom action (C#) are shown below. Any insight/help is greatly appreciated.

product.wxs file:

<Binary Id="CustomActionBinary" SourceFile="$(var.RegistryManagementCustomActions.TargetDir)$(var.RegistryManagementCustomActions.TargetName).CA.dll" />

<CustomAction Id="CustomActionAddRegistryEntries" Impersonate="no" BinaryKey="CustomActionBinary" DllEntry="AddRegistryEntries" Execute="deferred" Return="check" />

<CustomAction Id="CustomActionAddRegistryEntriesProperty" Property="CustomActionAddRegistryEntries"
                      Value="Arg1=1;Arg2=2;Arg3=3;INSTDIR=[INSTALLFOLDER]" />
    
<!--Installation Sequence-->
<InstallExecuteSequence>
 <!--add registry entries upon install-->
 <Custom Action='CustomActionAddRegistryEntries' After='InstallInitialize'>NOT Installed</Custom>
 <!--remove registry entries upon uninstall-->
 <Custom Action='CustomActionRemoveRegistryEntries' After='InstallFinalize'>
                (NOT UPGRADINGPRODUCTCODE) AND (REMOVE="ALL")
            </Custom>
 </InstallExecuteSequence>

Custom Action (C#) file:

[CustomAction]
        public static ActionResult AddRegistryEntries(Session session)
        {
            CustomActionData data = session.CustomActionData;
            string ss = data.Count.ToString() + "\n";
            foreach (var k in data)
            {
                ss += k.Key + ";" + k.Value + "\n";
            }
            //Access arguments
            //string arg1 = session.Format(data["Arg1"]);

            session.Log("Begin adding registry entries");
 
            string s = "Running AddRegistryEntries";
            s += "\n" + ss;

            File.WriteAllText(@"C:\Users\Bhairav\Desktop\customactiontest.txt", s);
            return ActionResult.Success;
        }

FIX: In the product.wix file (Towards the end of body): Fix: In the tag, towards the end:

<Binary Id="CustomActionBinary" SourceFile="$(var.RegistryManagementCustomActions.TargetDir)$(var.RegistryManagementCustomActions.TargetName).CA.dll" />
        <CustomAction Id="CustomActionAddRegistryEntries" Impersonate="no" BinaryKey="CustomActionBinary" DllEntry="AddRegistryEntries" Execute="deferred" Return="check" />
        <CustomAction Id="CustomActionAddRegistryEntriesProperty" Property="CustomActionAddRegistryEntries"
                      Value="InstallDir=[INSTALLFOLDER]" />

        <CustomAction Id="CustomActionRemoveRegistryEntries" Impersonate="no" BinaryKey="CustomActionBinary" DllEntry="RemoveRegistryEntries" Return="check" />

        <!--Installation Sequence-->
        <InstallExecuteSequence>
            <!--add registry entries upon install-->
            <Custom Action="CustomActionAddRegistryEntriesProperty" After="CostFinalize" />
            <Custom Action='CustomActionAddRegistryEntries' After='InstallInitialize'>NOT Installed</Custom>

            <!--remove registry entries upon uninstall-->
            <Custom Action='CustomActionRemoveRegistryEntries' After='InstallFinalize'>
                (NOT UPGRADINGPRODUCTCODE) AND (REMOVE="ALL")
            </Custom>
        </InstallExecuteSequence>

In the custom action (C#) side:

[CustomAction]
    public static ActionResult AddRegistryEntries(Session session)
    {
        CustomActionData data = session.CustomActionData;
        string installDir = data["InstallDir"];
        session.Log("Begin adding registry entries");
        session.Log("InstallDir = " + installDir);

        return ActionResult.Success;
    }

I hope this helps someone save some trouble.