Exception from WebService

Question

I have a question and i hope anyone could help me on this... I am testing a webservice project that calls an exception generator class. Actually, this exception generator is connected to the database and everytime i tried to change the connection so that it creates an error... the exception it generates is different to the exception raised by the webservice. For example, if the error message from exception generator is "Login failed for user "sa"!" the error message raised from web service is "Object reference not set to an instance of an object!" These error from web service only happens if I intentionally changed the connection of database. any idea would be of great help! Thanks! Chris.