Это ошибка в PhoneTextBox в Windows Phone?

Question

После применения стиля к PhoneTextBox что-то случилось странно.Сначала я ввел в него некоторый текст, затем удалил текст из phonetextbox, не теряя фокуса, затем снова ввел некоторый текст, но текст не виден.Но когда PhoneTextbox сфокусировался, текст снова появился.

Есть мысли по этому поводу?Спасибо.

Редактировать: стиль определяется как:

<Style x:Key="PhoneTextBoxStyle" TargetType="toolkit:PhoneTextBox">
        <Setter Property="FontFamily" Value="{StaticResource PhoneFontFamilyNormal}"/>
        <Setter Property="FontSize" Value="{StaticResource PhoneFontSizeMediumLarge}"/>
        <Setter Property="Background" Value="Transparent"/>
        <Setter Property="Foreground" Value="White"/>
        <Setter Property="BorderBrush" Value="White"/>
        <Setter Property="SelectionBackground" Value="{StaticResource PhoneAccentBrush}"/>
        <Setter Property="SelectionForeground" Value="White"/>
        <Setter Property="BorderThickness" Value="2"/>
        <Setter Property="Padding" Value="{StaticResource PhoneBorderThickness}"/>
        <Setter Property="CaretBrush" Value="White"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="toolkit:PhoneTextBox">
                    <Grid x:Name="RootGrid" Background="Transparent">
                        <VisualStateManager.VisualStateGroups>
                            <VisualStateGroup x:Name="CommonStates">
                                <VisualState x:Name="Disabled">
                                </VisualState>
                                <VisualState x:Name="Enabled">
                                </VisualState>
                            </VisualStateGroup>
                            <VisualStateGroup x:Name="FocusStates">
                                <VisualState x:Name="Focused">
                                </VisualState>
                                <VisualState x:Name="Unfocused"/>
                            </VisualStateGroup>
                        </VisualStateManager.VisualStateGroups>
                        <Border x:Name="LengthIndicatorBorder">
                            <TextBlock x:Name="LengthIndicator" Foreground="{StaticResource PhoneContrastBackgroundBrush}" FontSize="{StaticResource PhoneFontSizeNormal}" HorizontalAlignment="Right" Margin="0" Opacity="0" TextAlignment="Right" VerticalAlignment="Bottom">
                                    <TextBlock.RenderTransform>
                                        <TranslateTransform/>
                                    </TextBlock.RenderTransform>
                            </TextBlock>
                        </Border>
                        <Border x:Name="HintBorder" BorderBrush="{TemplateBinding BorderBrush}" 
                                BorderThickness="{TemplateBinding BorderThickness}" 
                                Background="{TemplateBinding Background}" Margin="0">
                            <Grid>
                                <ContentControl x:Name="HintContent" Background="Transparent" Content="{TemplateBinding Hint}"
                                                HorizontalAlignment="Left" Margin="3,5,3,0" Style="{TemplateBinding HintStyle}" 
                                                Foreground="White"
                                                Visibility="{TemplateBinding ActualHintVisibility}" VerticalAlignment="Top"/>
                                <ContentControl x:Name="ContentElement" BorderThickness="0" HorizontalContentAlignment="Stretch" 
                                                Margin="{StaticResource PhoneTextBoxInnerMargin}" 
                                                Padding="{TemplateBinding Padding}"
                                                VerticalContentAlignment="Stretch"
                                                Foreground="White"/>
                            </Grid>
                        </Border>
                        <Border x:Name="TextBorder" BorderBrush="{TemplateBinding BorderBrush}" 
                                BorderThickness="{TemplateBinding BorderThickness}" 
                                Background="Transparent" Margin="0" Visibility="Collapsed">
                            <TextBox x:Name="Text" Foreground="{StaticResource PhoneDisabledBrush}" 
                                     FontWeight="{TemplateBinding FontWeight}" FontStyle="{TemplateBinding FontStyle}" 
                                     FontSize="{TemplateBinding FontSize}" FontFamily="{TemplateBinding FontFamily}"
                                     HorizontalAlignment="Left" SelectionForeground="{TemplateBinding SelectionForeground}" 
                                     SelectionBackground="{TemplateBinding SelectionBackground}" 
                                     TextAlignment="{TemplateBinding TextAlignment}" TextWrapping="{TemplateBinding TextWrapping}" 
                                     Text="{TemplateBinding Text}"/>
                        </Border>
                        <Border x:Name="ActionIconBorder" Background="Transparent" HorizontalAlignment="Right" Height="54" VerticalAlignment="Bottom" Width="54">
                            <Image x:Name="ActionIcon" Height="54" Source="{TemplateBinding ActionIcon}" Width="54"/>
                        </Border>
                        <TextBlock x:Name="MeasurementTextBlock" FontWeight="{TemplateBinding FontWeight}" FontStyle="{TemplateBinding FontStyle}" FontStretch="{TemplateBinding FontStretch}" FontSize="{TemplateBinding FontSize}" FontFamily="{TemplateBinding FontFamily}" IsHitTestVisible="False" Margin="8" Opacity="0" TextAlignment="{TemplateBinding TextAlignment}" TextWrapping="{TemplateBinding TextWrapping}" Text="{TemplateBinding Text}"/>
                    </Grid>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>