SOAP client access problem

Hello,

As someone very new to SOAP, I'm trying to get a very simple SOAP client 
I wrote to talk to a simple SOAP service that I've deployed. I'm running 
into a problem.

The service is deployed under "urn:helloworld", and when I look at the 
deployed service information in the Apache SOAP admin app, everyting 
appears to be in order. However, When I run the client, I get a fault 
string "service 'urn:helloworld' unknown".

Are there any typical reasons why an URN listed in the admin app 
wouldn't be accessible by a SOAP client?

Thanks,
Jason