Interop Authentication AXIS server/ .net client

[CS]

Hi

I need to connect to an AXIS server using SSL. I've registered their
certificate in trusted roots, added the web reference and tried both
this:

Dim oService As New <webservice>
oService.PreAut henticate = True
oService.Creden tials = New
System.Net.Netw orkCredential(< username>,<pass word>)

and this:

Dim oService As New <webservice>
oService.PreAut henticate = True
Dim oCred As System.Net.Netw orkCredential = New
System.Net.Netw orkCredential(< username>, <password>)
Dim oCache As New System.Net.Cred entialCache
oCache.Add(New Uri(oService.Ur l), "basic", oCred)
oService.Creden tials = oCache
oService.Connec tionGroupName = <username>

both of which run fine. However, any attempt to use the web service
functions results in an 'access denied' error. The java client they
supplied me works fine with the same username and password:

Stub stub = (Stub) <webservice>;
stub._setProper ty(stub.USERNAM E_PROPERTY, <username>);
stub._setProper ty(stub.PASSWOR D_PROPERTY, <password>);

Any ideas as to what I could be doing wrong? [I don't have access to
the services logs or settings]

Full error:
An unhandled exception of type
'System.Web.Ser vices.Protocols .SoapException' occurred in
system.web.serv ices.dll

Additional information: Access denied.
Thanks!
CS