I am running VS2010 and have Expression Blend 3 installed.
I select a file, MainPage.xaml and select the option "Open in Expression Blend."
Expression Blend 3 is opened and my associated web application "SilverApplication1.Web" is displayed in the project explorer with the error "Unsupported project."
Any idea why?
You must be using Silverlight 4. Try downgrading to 3. Not sure if Expression Blend supports 4 yet. You may try the pre release beta of Expression 4.
Expression Blend 4 is required to understand VS2010 projects. Blend 3 does not. You may be eligible for a Blend 4 upgrade (if your Blend 3 is a part of a Studio installation). Details:
With this release comes a free Upgrade for licensed version 3 (Studio or Web) users! All you need to do is install the trial version of v4 on top of your licensed version of Expression Studio 3 or Expression Web 3 and the installer will find your license and upgrade it to the full v4 product with no expiration. This applies to customers who received their software through retail channels or electronic software download direct. For customers who have broader license agreements (i.e., MSDN, WebsiteSpark, BizSpark) you should install the product using the software provided from your program site.