HeaderBackgroundColor with AppThemeBinding

[eyeveye]

Hi,

When trying to switch Theme, the HeaderBackgroundColor does not reflect immediately. It only changed its color when reloading the whole page.

        HeaderBackgroundColor="{AppThemeBinding Dark=#353535,
                                                        Light=#00C8FF}" 

I tried to set the headerbackgroundcolor from code behind, but it is also not successfully change.
var tv = Page.FindByName("tv");
if (App.AppTheme == App.Theme.Dark)
{
tv.HeaderBackgroundColor = Color.FromHex("#353535");
}
else
tv.HeaderBackgroundColor = Color.FromHex("#00C8FF");