In my installation of Blend 3, the SketchStyles are missing when a new project is created. I found out that this is because the following automatic references in the project are wrong:
In the project references, these all point to my project path (where they don't live).
If I remove them manually, and instead set the references to ie this: "c:\Program Files (x86)\Microsoft SDKs\Expression\Blend 3\Interactivity\Libraries\Silverlight\Microsoft.Expression.Interactions.dll" everything works.
Any ideas on why, and how to fix this? Could it be the project template somehow?
Those assemblies are referenced just by name in the .csproj files, and use a registry key to resolve to the proper place, when they can't be found that way, they default to your project folder. I would say your installation is broken somehow, what did you use to install, and from where?
The simplest solution is probably to uninstall the Blend 3 SDK, and Blend 3, and then reinstall Blend 3. There were a couple of problems from back when Blend 3 was in preview state, so if you had the MIX preview or RCs installed, it could be related.
The registry keys are documented in this post from the Expression forums:
Here is more info:
You probably have two missing registry keys: (Note, these are for 64 bit machines, if you are in 32 bit, omit the Wow6432Node)
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Microsoft SDKs\Silverlight\v3.0\AssemblyFoldersEx\Expression SketchFlow
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Microsoft SDKs\Silverlight\v3.0\AssemblyFoldersEx\Expression Blend
If you enter the location of the Blend SDK there, then you should be up and running.
For the first registry path above, add a (Default) REG_SZ with Data: C:\Program Files\Microsoft SDKs\Expression\Blend 3\Interactivity\Libraries\Silverlight\
For the second path above, add a (Default) REG_SZ with Data: C:\Program Files\Microsoft SDKs\Expression\Blend 3\Prototyping\Libraries\Silverlight\