WPControls extension

WPControls extension

I have added WPControls extension, and having problems dealing with calendar.
This library can be found in NuGet by WPControls or by link:
https://wpcontrols.codeplex.com/
I found that calendar uses the devices CurrentCulture set in
Settings-Regional format.
But my application will have personnal setting - LV, ENG and RU.
I did this:
Thread.CurrentThread.CurrentCulture = new CultureInfo("lv-LV");
Which means CurrentCulture of application now is set to LV.
But calendar still uses devices regional format.
In Calendar properties i found this:

Is that what i am looking for?
And how to set it?
I tried this:
Cal.Language = CultureInfo.CurrentCulture;
But its a error:
Error 24 Cannot implicitly convert type 'System.Globalization.CultureInfo'
to 'System.Windows.Markup.XmlLanguage' C:\Users\afomenko\Documents\Visual
Studio 2012\Projects\WP8mobile\WP8mobile\CalendarPage.xaml.cs 126 28
WP8mobile