I am attempting to generate a Main Flow Path for a number of watersheds. I am using the tutorial for Arc Hydro Tools 2.0 and it states that before the Main Flow Path can be generated, the Populate Drain Area for Drainage Line needs to be run to create a new field (DrainArea) in the Drainage Line feature class. When I run the tool it fails to add the field. The error I get is shown below. Has anyone run into this issue before and what did you do to resolve it? I am wondering if other preprocessing needs to be done on the Catchment and Adjoint Catchment feature classes that are used as inputs, but I cannot find anything that speaks to that.