因为网格wp8.1通用而在SetValue上崩溃

Question

我试图在枢轴的一个部分设计瓷砖，其中有6个瓷砖，包括纵向和横向。我希望3x2（3rows）瓷砖用于纵向，2x3瓷砖用于横向。它在没有c＃代码的两种模式下显示3x2但在添加该代码后，它会在第一个Setvalue上崩溃。

我的xaml代码：

 <Grid>
                        <Grid.RowDefinitions>
                            <RowDefinition Height="172"/>
                            <RowDefinition Height="172"/>
                            <RowDefinition x:Name="more_3rdrow" Height="172"/>
                        </Grid.RowDefinitions>
                        <Grid.ColumnDefinitions>
                            <ColumnDefinition Width="172"/>
                            <ColumnDefinition Width="172"/>
                            <ColumnDefinition x:Name="more_3rdcolumn" Width="0"/>
                    </Grid.ColumnDefinitions>
                      <Grid Grid.Row="0" Grid.Column="0" x:Name="contacttile">
                         some data here
                      </Grid>
                      <Grid Grid.Row="0" Grid.Column="1" x:Name="ratetile">
                         some data here
                      </Grid>
                      <Grid Grid.Row="1" Grid.Column="0" x:Name="moreappstile">
                         some data here
                        </Grid>

                      more grids here
</Grid>

我的c＃代码：

     private void pivot_Loaded(object sender, RoutedEventArgs e)
   {
       moresectionLoaded = 1;
   }
     private void PageBase_SizeChanged(object sender, SizeChangedEventArgs e)
   {

       if (moresectionLoaded == 1)
       {


       string currentviewstate = ApplicationView.GetForCurrentView().Orientation.ToString();
       if (currentviewstate == "Portrait")
       {
           ///crashes in below line
           more_3rdrow.SetValue(RowDefinition.HeightProperty, 172);
           more_3rdcolumn.SetValue(ColumnDefinition.WidthProperty, 0);

           moreappstile.SetValue(Grid.RowProperty, 1);
           moreappstile.SetValue(Grid.ColumnProperty, 0);

           abouttile.SetValue(Grid.RowProperty, 1);
           abouttile.SetValue(Grid.ColumnProperty, 1);

           pintile.SetValue(Grid.RowProperty, 2);
           pintile.SetValue(Grid.ColumnProperty, 0);

           pintypestile.SetValue(Grid.RowProperty, 2);
           pintypestile.SetValue(Grid.ColumnProperty, 1);
       }
       if (currentviewstate == "Landscape")
       {

           ///crashes in below line
           more_3rdrow.SetValue(RowDefinition.HeightProperty, 0);
           more_3rdcolumn.SetValue(ColumnDefinition.WidthProperty, 172);

           moreappstile.SetValue(Grid.RowProperty, 0);
           moreappstile.SetValue(Grid.ColumnProperty, 2);

           abouttile.SetValue(Grid.RowProperty, 1);
           abouttile.SetValue(Grid.ColumnProperty, 0);

           pintile.SetValue(Grid.RowProperty, 1);
           pintile.SetValue(Grid.ColumnProperty, 1);

           pintypestile.SetValue(Grid.RowProperty, 1);
           pintypestile.SetValue(Grid.ColumnProperty, 2);
       }
       }
   }