MS Project 2013 Workflow Platform not available in SharePoint Designer 2013

Hi,

I installed and configured SharePoint 2013 Workflow on SharePoint 2013 server according to this article:

http://technet.microsoft.com/en-us/library/jj658588.aspx#section4

I also have MS Project 2013 installed on the same server where SharePoint 2013 resides. Everything works fine. I can create MS Project site and so on. The only problem is that when I open SharePoint Designer 2013 (Open Project Site) and click Site Workflow there are only two options under Workflow Platform Type in Create Site Workflow: 1. SharePoint 2013 Workflow and SharePoint 2010 Workflow.

I presume when I did installation according to the link above it supposed to activate SharePoint 2013 Workflow for Project Server.

Could you please help to find out why MS Project Workflow is not available?

Thank you.