I am having an syntax error from Pyscripter here and not sure why but I have a shapefile at the top of the TOC list which is the first and should be number zero when writing a listlayers as a zero but I still get the error .
The error is :
Traceback (most recent call last):
File "C:\Student\python\GeoTIFF.py", line 16, in <module>
gridlayer = arcpy.mapping.ListLayers(mxd,'JERGRIDINDEX', df,)[0]
IndexError: list index out of range
Take a look here the sytanx:: gridlayer = arcpy.mapping.ListLayers(mxd,'JERGRIDINDEX', df,)[0]