Spatial Reference not set

Discussion created by lsgiswater on Jul 3, 2012
Latest reply on Jul 17, 2013 by ajay_more
I am using ArcGIS10 with HEC Geo-HMS for input into GEO-RAS. Everything has gone well until I get to Longest Flow Path under Characteristics. I am getting the message ???The Spatial Reference is not set for the inputs.??? My DEM is from LiDAR, UTM zone 15N NAD 83, as is my view and the other two inputs, flow direction grid and subbasin.  Any advice is greatly appreciated.