Usage IN Code,if i change the Language,the string can't change

[pengqi1991]

if i have a title,
in resx, the apptitle is "app";
in the code
public string Title
{
get { return GetValue(); }
set { SetValue(value); }
}
ctor{
Title= Translate.Key(nameof(Resources.apptitle)) + " 1.0.0";
}
in xaml

When i change the language,the Title Can't change.