When using the point dispersion sample extension with a geocoded theme, the following error is returned:
"Can't convert string to number: Number Null"
There are unmatched results in your geocoded theme. These unmatched records do not have any shapes associated with them. When the extension tries to get the coordinate values for the feature it gets a Null value, and errors out of its operation.
( [Av_status] = "U" )