this.z_plan_name_Edit.LoadDDSByNavigationContext(this.NavigationContext);

     public IQueryable<z_plan_name> GetZ_plan_name_Edit(int id)
        {
            return this.ObjectContext.z_plan_name;
        }

     public IQueryable<z_plan_name> GetZ_plan_name_Edit(int id)
        {
            return this.ObjectContext.z_plan_name.Include("name").Where(r => r.id == id);;
        }

The GetZ_plan_name_Edit method does not have arguments that match the QueryParameters collection.

   public IQueryable<Customer> GetCustomerById(int Id)
        {
            return this.ObjectContext.Customer.Where(r => r.Id == Id);
        }

       <navigationCore:UriMapping Uri="Customer/Edit/{Id}" MappedUri="/Views/fCustomer/Edit.xaml?Id={Id}"/>

  NavigationService.Navigate(new Uri("/Plan/Page_Edit.xaml?Id={Id}", UriKind.RelativeOrAbsolute));

 <Button Content="Button" Name="button1" Click="button1_Click" Tag="Plan/Page_add.xaml"/>

     ChildWindow childWindow = TreeHelper.FindVisualParent<ChildWindow>(this);
            if (childWindow != null)
            {
                childWindow.Width =  700 ;
                childWindow.Height =  310 ;
                Button navigationbutton = sender as Button;
                String goToPage = navigationbutton.Tag.ToString();
                NavigationService.Navigate(new Uri(goToPage, UriKind.Relative));
            }

 <navigationCore:UriMapper x:Key="AppURIMapper">
        <navigationCore:UriMapping Uri="Plan/Page_add" MappedUri="/Plan/Page_add.xaml"/>
 </navigationCore:UriMapper>

 <Button Content="Button" Name="button1" Click="button1_Click" Tag="Plan/Page_add.xaml"/>

 GridCellMenuInfo menuInfo = Control_Plan.GridMenu.MenuInfo as GridCellMenuInfo;
                if (menuInfo != null && menuInfo.Row != null)
                {
                    menuInfo.Row.Row.ToString();//точка остановка
                }

   z_plan_name ID_Plan = menuInfo.Row.Row as z_plan_name;
                    ID = ID_Plan.id;

<ComboBox x:Name="User_ComboBox" ItemsSource="{Binding Mode=OneWay, ElementName=z_userDomainDataSource, Path=Data}" 
             DisplayMemberPath="UserName" Margin="167,29,12,23" Grid.RowSpan="2" />
<TextBlock Grid.Row="2" Height="23" HorizontalAlignment="Left" Margin="3,7,0,0" 
                   Name="User_Text_Pass" Text="{Binding Path=Data.User, Mode=OneWay, ElementName=z_userDomainDataSource}" 
                   VerticalAlignment="Top" Visibility="Collapsed" />

<TextBox HorizontalAlignment="Left" Margin="105,12,0,0" Name="User_TextEdit" 
                 VerticalAlignment="Top" Width="295" Height="23"  
                 Text = "{Binding Path=Data.UserName, Mode=OneWay, ElementName=z_userDomainDataSource}"/>

z_userDomainDataSource.Data.ToString(); //Точка останова

<toolkit:DataField Label="Имя" FontWeight="Bold" >
                            <TextBox Name="Name_1" Text="{Binding Path=Pass, Mode=TwoWay}" 
                                     FontWeight="Normal" />
                        </toolkit:DataField>