When you install the SharePoint Adapter Web Service for BizTalk, and browse to the BTSharePointAdapterWS.asmx Web Service, you will be prompted with an error that makes it seem like your installation of this Web Service was not successful:
Server Error in '/BTSharePointAdapterWS' Application.
Request format is unrecognized.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.InvalidOperationException: Request format is unrecognized
In fact your Web Service may be functioning correctly as mine was. The issue is that the Service metadata is disabled by default. To enable the Service metadata, you will need to update the web.config of the BTSharePointAdapterWS Application
Comment out, or remove the <remove name="Documentation"/> line in order to enable displaying the Service metadata.
Metadata will now be displayed correctly.