I'm using a Python script with ArcGIS 10 to count the number of unique string values in a feature class. My script works if there are values in the field but if there are any NUll values in the field it crashes. Any Ideas?

My code is below:

```
import arcpy
import operator

inTable = arcpy.GetParameterAsText(0)
stringField = arcpy.GetParameterAsText(1)

stringList = [row.getValue(stringField) for row in arcpy.SearchCursor
                                       (inTable, "", "",stringField)]

```