Creating New Route Event Data

[MarkOberg]

I am using ArcMap and ArcCatalog 10.3 with a Map Document (.mxd) and Personal GeoDatabase (.mdb).  There currently is one line feature class to indicate pipes on the map.  The goal is to indicate observations on the map as route events.  The first thing I do is create the new route feature class using the "Create Routes" tool in ArcMap with the existing line feature class as input.  The route ID field is text called PIPE_ID.  and the measure source is LENGTH.  This works well.  Now in ArcCatalog, I create a new table that will be the source for the route events.  According to documentation I've read, the minimum for fields is a measure field that needs to be numeric and the route ID field.  So the table contains OBJECTID, PIPE_ID (same data type), and MEASURE (as a double).  Back in ArcMap, I use the "Make Route Event Layer" tool with the route feature class and table previously made as inputs.  This creation goes well.  So currently there are no points and I would like to begin editing, but when I start editing, ArcMap tells me that my new route event layer is not editable.  Why is this? 

Warning: Event layer not editable—Help | ArcGIS for Desktop

There is an ObjectID field in the new table I created.  What else do I need to do?

Thanks in Advance,

Mark Oberg