Null Values in the table for the Catchment polygon

Discussion created by jkarr on Mar 3, 2011
Latest reply on Mar 28, 2011 by maulding
I ran the Catchment Polygon Process and it was successfull.  However, upon further investigation of the polygon table, the ArcHydroID and GridID fields were Null.  Later on in my workflow, I came to the "Ajoint Catchment Process" and got this error:

"Error occurered while computer Adjoint Catchment!  Invalid use of Null."

Any ideas how to fix this?