000289 : Failed to alter spatial reference.
The spatial reference of the dataset cannot be altered. The dataset may be in use by another application and therefore locked.
Ensure that the dataset is not read-only or being locked by another application or user
import arcpy # coordinateSystem = "C:/Program Files (x86)/ArcGIS/Desktop10.0/Coordinate Systems/Geographic Coordinate Systems/World/WGS 1984.prj" coordinateSystem = "GEOGCS['GCS_WGS_1984',DATUM['D_WGS_1984',SPHEROID['WGS_1984',6378137.0,298.257223563]],PRIMEM['Greenwich',0.0],UNIT['Degree',0.0174532925199433]]" tin = "habop-1999-04-avgcombinedSVT" wdir = "c:/path/TINS" arcpy.env.workspace = wdir desc = arcpy.Describe(tin) try: d = arcpy.DefineProjection_management(tin, coordinateSystem) except: print tin+" conversion no good."