MVVM WPF Command not firing - wpf

Question

I have MVVM WPF application. I create Menu via a separate service and set to load time.
My shell view which contains the menu is as follows:
<ItemsControl x:Name="MainToolbar" cal:RegionManager.RegionName="{x:Static inf:RegionNames.MainToolBarRegion}" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="1,1,1,1" RenderTransformOrigin="-0.133,-5.917" Height="28" >
<ItemsControl.RenderTransform>
<TransformGroup>
<ScaleTransform/>
<SkewTransform/>
<RotateTransform/>
<TranslateTransform/>
</TransformGroup>
</ItemsControl.RenderTransform>
<Menu IsMainMenu="True" Margin="0,0,0,0" Height="28" ItemsSource="{Binding Path=Menu}" Width="400">
<Menu.Resources>
<Style x:Key="ThemeMenuItemStyle" TargetType="MenuItem" BasedOn="{StaticResource KV_MenuItem}">
<Setter Property="Header" Value="{Binding Path=Text}"></Setter>
<Setter Property="Command" Value="{Binding Path=Command}"/>
<Setter Property="CommandParameter" Value="{Binding Path=Text}"/>
<Setter Property="IsCheckable" Value="True"/>
<Setter Property="MinWidth" Value="80"/>
</Style>
</Menu.Resources>
</Menu>
</ItemsControl>
MenuItem has a view model behind:
public class MenuItemViewModel : NotificationObject
{
private string text;
private ICommand command;
private IList<MenuItemViewModel> menuItems;
public MenuItemViewModel()
{
this.menuItems = new List<MenuItemViewModel>();
}
public string Text
{
get
{
return text;
}
set
{
if (text != value)
{
text = value;
RaisePropertyChanged(() => this.Text);
}
}
}
public ICommand Command
{
get
{
return command;
}
set
{
if (command != value)
{
command = value;
RaisePropertyChanged(() => this.Command);
}
}
}
public IList<MenuItemViewModel> MenuItems
{
get { return menuItems; }
set
{
if (menuItems != value)
{
menuItems = value;
RaisePropertyChanged(() => this.MenuItems);
}
}
}
}
My Relay command:
public class RelayCommand : ICommand
{
#region Fields
readonly Action<object> _execute;
readonly Predicate<object> _canExecute;
#endregion // Fields
#region Constructors
/// <summary>
/// Creates a new command that can always execute.
/// </summary>
/// <param name="execute">The execution logic.</param>
public RelayCommand(Action<object> execute)
: this(execute, null)
{
}
/// <summary>
/// Creates a new command.
/// </summary>
/// <param name="execute">The execution logic.</param>
/// <param name="canExecute">The execution status logic.</param>
public RelayCommand(Action<object> execute, Predicate<object> canExecute)
{
if (execute == null)
throw new ArgumentNullException("execute");
_execute = execute;
_canExecute = canExecute;
}
#endregion // Constructors
#region ICommand Members
[DebuggerStepThrough]
public bool CanExecute(object parameter)
{
return _canExecute == null ? true : _canExecute(parameter);
}
public event EventHandler CanExecuteChanged
{
add { CommandManager.RequerySuggested += value; }
remove { CommandManager.RequerySuggested -= value; }
}
public void Execute(object parameter)
{
_execute(parameter);
}
#endregion // ICommand Members
}
In menu service, I assign the command object like follows:
...
MenuItemViewModel app = new MenuItemViewModel();
app.Text = "APP";
app.Command = new RelayCommand(
param => this.App(""),
param => true);
MenuItemViewModel exit = new MenuItemViewModel();
exit.Text = "Exit";
exit.Command = new RelayCommand(
param => this.Exit(""),
param => this.CanExit
);
app.MenuItems.Add(exit);
mService.AddMenu(app);
...
My MenuItem is loading fine with assigned header text, but when I click a menu item it is not firing the relevant delegate methods such App("") or Exit("")
What I am doing wrong?