The tag 'DisplayObject' does not exist in XML namespace

I have a class called DisplayObject, its namespace is SilverlightClasses.Display
This is in a .dll file called SilverlightClasses.dll

I created a new project called InfluencecTest.When I try to create a Button and have it inherit from the DisplayObject class, I run into problems

I open up DoButton.xaml, and have it extend the DisplayObject class, take note of the myClassPath namespace

<myClassPath:DisplayObject
xmlns=“http://schemas.microsoft.com/winfx/2006/xaml/presentation
xmlns:x=“http://schemas.microsoft.com/winfx/2006/xaml
xmlns:d=“http://schemas.microsoft.com/expression/blend/2008
xmlns:mc=“http://schemas.openxmlformats.org/markup-compatibility/2006
xmlns:myClassPath =“clr-namespace:SilverlightClasses.Display;assembly=SilverlightClasses”
mc:Ignorable=“d”
x:Class=“InfluenceTest.DoButton”
d:DesignWidth=“166” d:DesignHeight=“41”>

&lt;Grid x:Name="LayoutRoot"&gt;
	&lt;Button Content="Button"/&gt;
&lt;/Grid&gt;

</myClassPath:DisplayObject>

This doesn’t work: error below, what am I doing wrong. DisplayObject does in fact exist because I can instantiate it directy inside any .cs file, xaml is the one that gives me problems

Error 1 The tag ‘DisplayObject’ does not exist in XML namespace ‘clr-namespace:SilverlightClasses.Display;assembly=SilverlightClasses’.