When trying to create a web reference to an existing web service you may see one or both of the following messages
Unabled to create web reference
Failed to create web rererence
If you see these messages (or similar messages), open up the source code (if you have it) from the service that you are trying to consume. Examine the attributes of the webmethods. See if there is a “Name” attribute on the methods, and remove it if there is. After you have done this you should be able to create the web reference from the BizTalk project.
I'm not sure why this works, but it has worked for me many times. If you can't alter the attributes on the webservice, you can try using a C# class library to create the web reference for you and then call it indirectly. It's messy I know, but it works.