A: 

It looks like you have typos in your XAML:

Alubm instead of Album and BlentTest instead of BlendTest

I'm guessing the errors are actually true compiler errors, and correcting the two typos above will most likely "fix" the designer.


Edit:

The most likely candidate that I see is that your converter is in a separate project from your XAML file (but in the same solution). If that's the case, make sure to specify the assembly in the XAML declaration, and make sure the other project (with BlendTest) is referenced correctly. ie:

xmlns:local="clr-namespace:BlendTest;assembly:BlendTest"

If your referring to a type (with namespace) defined in a different project, the assembly reference needs to exist, as well.

Reed Copsey
No, the typos are consistent enough for it to compile :)
ArielBH
It's not successfully compiling. It's showing you actual compile errors in your XAML file at the bottom of the window.
Reed Copsey
This is part of the problem. Visual Stdio compile it without problems, Blend compile it without problems (the output window indicate "The build has successfully completed.")
ArielBH
Are your converters (that are being referenced there) created with public visibility? If they're private, it may cause issues in the designer.
Reed Copsey
Nope, both are public.
ArielBH
Can you edit your question to include the XAML, both the namespace section, and the lines that are erroring? Without that, there's no way to debug this further.
Reed Copsey
Done. Thanks for the help
ArielBH
No, it's on the same project.
ArielBH
A: 

Well, while the cause of the problem is still unknown to me.

The solution to the mess was as followed:

  1. I've created a new Code Library project, and moved there all my controls and converters.

  2. I used the XmlnsDefinition attribute to decorate the assembly so each was corresponding to the same namespace.

  3. fixing all the references.

and Voilà.

Ariel

ArielBH
Wish they would fix this...
Kelly