BizTalk 2010：具有基于声明的身份验证的SharePoint REST

I'm trying to call one of the standard REST (ODATA) services to get data from a list in SharePoint. But I have issues with the claims based authentication. I'm using BizTalk 2010 with the REST starter kit extension. The sendport I'm using is a WCF-Custom with webHttpBinding. The error I get is the following.I'm trying to call one of the standard REST (OD