Что такое следующая ошибка?
Неоднозначный тип ссылки. Тип с именем "VisualState" встречается, по крайней мере, в двух пространствах имен "System.Windows" и "System.Windows". Рассмотрим настройку атрибутов сборки XmlnsDefinition.
usercontrol:
<UserControl
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"
mc:Ignorable="d"
x:Class="ButtonWPF.MyButtonAdd"
x:Name="AddButton"
d:DesignWidth="84" d:DesignHeight="87">
<UserControl.Resources>
<Style x:Key="ButtonStyle1" TargetType="{x:Type Button}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type Button}">
<Grid x:Name="grid" RenderTransformOrigin="0.5,0.5">
<Grid.RenderTransform>
<TransformGroup>
<ScaleTransform/>
.............
<Trigger Property="IsDefaulted" Value="True"/>
<Trigger Property="IsMouseOver" Value="True"/>
<Trigger Property="IsPressed" Value="True"/>
<Trigger Property="IsEnabled" Value="False"/>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</UserControl.Resources>
<Grid x:Name="LayoutRoot" Height="79" Width="72">
<Button Content="" HorizontalAlignment="Left" Height="61" Style="{DynamicResource ButtonStyle1}" VerticalAlignment="Top" Width="57"/>
</Grid>
mainWindow:
<Window x:Class="ButtonWPF.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:dg="http://schemas.microsoft.com/wpf/2008/toolkit"
Title="winGroup" Height="637" Width="638" xmlns:my="clr-namespace:ButtonWPF" FontSize="15" FontWeight="Bold">
<Grid >
<my:MyButtonAdd HorizontalAlignment="Left" Margin="540,519,0,0" x:Name="btnAdd" VerticalAlignment="Top" IsEnabled="True" />
</Grid>