The tag "XXX" does not exist in xml namespace

My SolutionName: TestBA My AssemblyName: TestBA

Default namespace: Examples.Bootstrapper

In TestBA assemble I have Converters folder:

namespace Examples.Bootstrapper.Converters
{
    class PercentToPixelsConverter : IValueConverter
(...)

I trying to use:

xmlns:c="clr-namespace:Examples.Bootstrapper.Converters;assembly=TestBA"

(...)

<c:PercentToPixelsConverter x:Key="MyName" />

I get an error:

The tag 'PercentToPixelsConverter' does not exist in XML namespace 'clr-namespace:Converters;assembly=TestBA'.