WebService-Error: "the found request-type is 'text/html; charset=utf-8', but 'text/xml' was expected"

Hello NG!

I try to call a WebService from a mobile device. The WebService should
return a DataSet, so the call looks like

mDataSet = mWebSrv.GetDataSet(<Params>)

but instead of returning a DataSet, that call throws an error:

InvalidOperationException
"the found request-type is 'text/html; charset=utf-8', but 'text/xml' was
expected"

(or something like that, it's a german system)

I guess that's because ASP.NET tries to send a html-formated message to my
mobile device about an error occured on the server, right? That error only
occurs on the deploy-server, with an 'ide-connected' server on my lokal
workstation it works.

Is there a possibility to avoid this behaviour? And how to get the real
message which is within the received html? I thougth the return of a
WebService always is XML (SOAP), why ASP.NET tries to send back html?

Or is there an other reason for that error?

Thanks, D.Barisch