Text Rotation inside grid. Strange behavior

Hi, please take a loook to this short piece of xaml :

 <ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" x:Class="vertical.griglia">
<ContentPage.Content>
    <Grid VerticalOptions="FillAndExpand" HorizontalOptions="FillAndExpand">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="90*"></ColumnDefinition>
            <ColumnDefinition Width="10*"></ColumnDefinition>
        </Grid.ColumnDefinitions>

        <StackLayout Padding="-100,100,100,0" Grid.Column="0"  Grid.ColumnSpan="1" HorizontalOptions="FillAndExpand"     VerticalOptions="Fill" BackgroundColor="Olive">
            <Label Rotation = "-90" TextColor="Aqua" Text="Ornella ruzzarin" AnchorY="0.5" YAlign="End"></Label>
            </StackLayout>
    </Grid>

</ContentPage.Content>

If you look to first screenshot you will se a label, correctly rotated on the screen. I made simple adjustment with paddings.
My goal is to display the label on column 1 (intstead of 0).

If i change Grid.Column and i set it to 1, i have a strange behavior.
Please take a look to the second Screenshot.(weird)

i have played with ALL possible properties "fill, fillandexpand" etc but i am not able to make the lable stay inside column 1.
Any suggestion ?

Thanks
Alessandro