I have an SDK script activity in my Workflow. It is very very simple:

namespace WorkflowActivity.Scripting.SDKScript2
{
    using System;
    using System.Collections.Generic;
    using System.ComponentModel;
    using System.Data;
    using System.Data.SqlClient;
    using System.Text;
    using Laserfiche.RepositoryAccess;

    public class Script1 : RAScriptClass102
    {
        protected override void Execute()
        {
            
            DocumentInfo di = this.BoundEntryInfo as DocumentInfo;
            DesignTools.Watch("document path", di.Path);
        }
    }
}

This results in an error when run on a starting entry:

The "di" object seems to be null and I'm trying to understand why. WF connection profile is valid, and the starting entry exists (it's a PDF doc).