arcgis 10.2 - ArcPy function works in ArcMap Python window but not from standalone script?

So I think I'm running into a data/schema lock issue, but I have no idea how to tell, or how to fix it for that matter. Here's the setup:

I have this chain of gp functions:

#extract elevations to stations
arcpy.gp.ExtractValuesToPoints_sa(station_locations, elevation_raster, scratchGDB + "\station_elevations", "NONE", "VALUE_ONLY")

#calculate the mean air temperature for each station over the n-hour time period
arcpy.Statistics_analysis(data_table, scratchGDB + "\station_statistics", "air_temperature MEAN", "site_key")
#join elevations to the statistics table created above
arcpy.JoinField_management(scratchGDB + "\station_statistics", "site_key", scratchGDB + "\station_elevations", "Site_Key", "RASTERVALU")
#select rows in "station_statistics" that have a positive elevation (non-null)
arcpy.TableSelect_analysis(scratchGDB + "\station_statistics", "stats1", "RASTERVALU IS NOT NULL")

scratchGDB is set from:

scratchGDB = arcpy.env.scratchGDB

When I run these four gp functions one at a time in the ArcMap python window, they run successfully. But when I run the debug in PyScripter on the stand-alone script, I get this error from the "arcpy.TableSelect_analysis" function:

Looking into "ERROR 000210" is what makes me think it's a data lock issue, but I'd like to know what's making it work in the python window and not work in the PyScripter IDE?

Answer

I don't see where you set the env so try changing your Table Select line to:

arcpy.TableSelect_analysis(scratchGDB + "\station_statistics", scratchGDB + "\stats1", "RASTERVALU IS NOT NULL")