Administrator may need to add a new request Url mapping to the intended application

Scenario:
I was trying Visual Studio Extension for Workflow and go the following error while creating a new workflow. I added a new project , it poped-up a screen asking for the Url to the site , I want to attach the workflow... now the thing is it already had a default value 'http://spvm/docs' and if i go ahead with the default value, it gave me error saying -- Check for the Url to the site , Administrator may need to add a new request Url mapping to the intended application

Solution:
Basically its very simple , wizard expect Url to the site and not the document library or list you want to attach workflow. So I changed the Url from

http://spvm/docs >> http://spvm

and it worked.