prevent exception if user enters invalid address for geocoding within create user wizard?

hi,
I am using google geocoding to to take a street address and City values from 2 textboxes which
are within a create user wizard. The lat and long values are then assigned to object data source parameters.

if the user does not enter a valid street address then I get an exception and this
prevents the createuserwizard from completing.

Instead of this- if the code is not valid I just want to continue and not
show the user an exception. 
however the Lat and Longitude are required by the ObjectDataSource6 Insert statement
that follows the above code block. If the address is not read then I guess I want to
prevent the InsertStatement as well?

Could you please demonstrate how to solve the problem?


Server Error in '/' Application. Object reference not set to an instance of an object. ...