Webservice access problem

[Odin Jensen]

I've made a webservice which can be called from a C# client we use.
Now I wanted to make a function on the webservice to test some
connection functionality the webservice uses and I wanted to call that
from the normal webinterface that's autogenerated my VS.NET.

The problem is that the normal webservice calls that are called from
C# works, but the webcall fails first with a HTTP 500 - Internal
server error and then when you press F5 you get a
System.InvalidOperationException: Requested format not recognized (do
not know the exact error here as my damn .NET is in Danish

I use automatic WSE authentication, but even if I turn it off it does
not work.

Anyone?

Thanks in advance

Odin Jensen