File not found after I just successfully loaded assembly

I am loading two assemblies using reflection and then using a few types from them. After I load the assembly, load a type and then instantiate a type with Activator, I get a FileNotFound exception on the assembly when trying to invoke a "LoadFromXml" method. This was previously working and I cannot figure out what changed. Also, I can get a property from the created instance without a problem. It's only throwing exceptions when invoking the method "LoadFromXml."

 private static object CheckForVersion(int version, string constructFilePath, string utilityFilePath)
    {
        if (!System.IO.File.Exists(constructFilePath) || !System.IO.File.Exists(utilityFilePath) || version < 7) return null;

        var utilAssembly = System.Reflection.Assembly.LoadFile(utilityFilePath);
        var constructAssembly = System.Reflection.Assembly.LoadFile(constructFilePath);

        var InfoManager = utilAssembly.GetType(String.Format("{0}.InfoManager", utilAssembly.FullName.Split(',')[0]));
        var ExecutionServerPropertiesConstructType = constructAssembly.GetType(String.Format("{0}.ExecutionServerPropertiesConstruct", constructAssembly.FullName.Split(',')[0]));

        string dbFolder = (string)(InfoManager.GetProperty("ServerDatabaseFolder").GetValue(null, null));

        if (Directory.Exists(dbFolder) == true)
        {
            string FilePath = Path.Combine(dbFolder, @"ExecutionServer.config.xml");                    //DONT LOCALIZE

            dynamic theServerProperties = Activator.CreateInstance(ExecutionServerPropertiesConstructType);

            theServerProperties.LoadFromXml(FilePath);

            var retVal = new
            {
                InstalledProductVersion = version,
                ServerGuid = (string)InfoManager.GetField("SERVER_GUID").GetValue(null),
                WorkflowRootnodeGuid = (string)InfoManager.GetField("WORKFLOW_ROOTNODE_GUID").GetValue(null),
                TaskRootnodeGuid = (string)InfoManager.GetField("TASK_ROOTNODE_GUID").GetValue(null),
                TriggerRootnodeGuid = (string)InfoManager.GetField("TRIGGER_ROOTNODE_GUID").GetValue(null),
                ProcessRootnodeGuid = (string)InfoManager.GetField("PROCESS_ROOTNODE_GUID").GetValue(null),
                ConnectionString = theServerProperties.ConnectionString
            };

            return Newtonsoft.Json.JsonConvert.SerializeObject(retVal);
        }

        return null;
    }