New clients to the Map Magic rectangle selection tool will sometimes get results of no data or an incorrect number of collisions. However, this problem will not occur with the send selected collisions tool.
Map Magic > Data
In many cases, your GIS map street names will not match the names in your crash record database. If the difference is significant, (i.e. ArcView can't see them as being similar names) then that location will not be geocodable. This is common when a state highway runs through a city. The city may use a local street name when entering crash data, and the map may use the highway name.