Loading a raster into a dataframe in arcpy

Question

When attempting to load a raster (created in arcpy) using arcpy.mapping.AddLayer, I get the following error message:

Here's a snippet of the code:
env.workspace = arcpy.GetParameterAsText(0)
...
YmapFile      = arcpy.GetParameterAsText(4) # Output filename
...
YMAP = arcpy.NumPyArrayToRaster(YmapArray,lowerLeft,pixSize,pixSize)
YMAP.save(YmapFile)
...
mxd = arcpy.mapping.MapDocument("CURRENT")
df    = arcpy.mapping.ListDataFrames(mxd)[0]
arcpy.MakeRasterLayer_management(YmapFile,"Y Map")
arcpy.mapping.AddLayer(df,"Y Map", "BOTTOM")

The raster is properly created and saved in the folder/geodatabase defined by env.workspace.

Also, I can load the raster layer using the arcpy.SetParameterAsText() function (when the parameter is set as a derived entity in the scipt's properties option box), so I know that the layer is being properly created.

Any suggestions?

JasonScheirer · Accepted Answer

You'll need to save a raster layer as a .lyr file to disk with the symbology you want, then use arcpy.mapping.Layer to open the layer file and set the dataSoruce attribute to the source of the new raster you've created.