Hello,
Project 2007 documentation says :
In previous versions of Project, the project plan was automatically published when you closed a project, if it had been saved prior to closing. In Office Project Professional 2007, changes you make are saved to a local copy of the project plan. The local copy is not published until you choose to publish it.
I can publish a new project but once it's modified I am not able to publish the changes I have made :
http://images.sherweb.com/images/publish.jpg 
I can only publish with a different name each time...
Is it because Project did not detect an active workspace for this project ?
Does anyone have an idea of how I could save my changes so they could appear in Project Web Access ?
Thank you