MVVM Binding in Silverlight3 ItemsControl to get the parent controls DataContext - silverlight

Question

I have the following ItemsControl in Silverlight 3.
<ItemsControl ItemsSource="{Binding ValueCollectionList}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<Button x:Name="MyBtn" Height="40" Content="{Binding Name}"
Tag="{Binding Value}"
cmd:ButtonBaseExtensions.Command="{Binding ElementName=LayoutRoot, Path=ButtonCommand}"
cmd:ButtonBaseExtensions.CommandParameter="{Binding ElementName=MyBtn, Path=Tag}"/>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
The Problem is that I have the ItemsControl bound to the Collection in my ViewModel, but I need the button to trigger a command on the ViewModel which is of course not Available in the DataContext of the button since it only contains the collection.
I can make the command fire by setting my ViewModel as a Resource and then binding to it as a StaticResource, but I want to know why the element to element binding won't work in this scenario. I would prefer not to use the StaticResource binding because that requires the default constructor on the ViewModel and so I can't inject my data easily.
UPDATE
I'm working through this slowly... Looking at the suggestions from Peter I realized that I may have more serious binding issues because of my page setup. I have two possible road blocks, but first things first.
My Items control above is wrapped in another items control that is bound to an observable collection. I moved my items control so that its a direct child of the root items control. It was wrapped in another control that I'll get to. So I tried the element binding to the items control ControlItemList, but its a collection so it can't find my ButtonCommand method in that Collection. What I need to do is bind to an item within that collection. How do I bind to a single item within the collection?
<Grid x:Name="LayoutRoot" Background="White"><!-- DataContext="{Binding Path=., Source={StaticResource lvvm}}">-->
<StackPanel Orientation="Vertical">
<ItemsControl x:Name="ControlItemList" ItemsSource="{Binding}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition MinWidth="100" />
<ColumnDefinition Width="*" />
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<TextBlock x:Name="ControlName" Grid.Column="0" Text="{Binding Name}" VerticalAlignment="Center" />
<ItemsControl ItemsSource="{Binding ValueCollectionList}">
<ItemsControl.ItemTemplate>
<DataTemplate>
So, Assuming I can get the above to work the other road block is that my items control is wrapped in another usercontrol that I'm using to get DataTemplateSelector type functionality. I think this control may be blocking me from getting to the parent DataContext. Is there a limit as to how far up the tree you can go?
<common:DeviceControlTemplateSelector Grid.Column="1" FieldType="{Binding ValueType}" Margin="0,2,0,2">
<common:DeviceControlTemplateSelector.StringTemplate>
<DataTemplate>
<TextBox Text="{Binding Value, Mode=TwoWay}" Width="100"/>
</DataTemplate>
</common:DeviceControlTemplateSelector.StringTemplate>
<common:DeviceControlTemplateSelector.DateTimeTemplate>
<DataTemplate>
<TextBox Text="this is date time binding" Width="100"/>
</DataTemplate>
</common:DeviceControlTemplateSelector.DateTimeTemplate>
<common:DeviceControlTemplateSelector.BooleanTemplate>
<DataTemplate>
<CheckBox IsChecked="{Binding Value, Mode=TwoWay}" />
</DataTemplate>
</common:DeviceControlTemplateSelector.BooleanTemplate>
<common:DeviceControlTemplateSelector.IntegerTemplate>
<DataTemplate>
<ComboBox ItemsSource="{Binding ValueCollection}" DisplayMemberPath="Value" SelectedIndex="{Binding Value, Mode=TwoWay}" >
</ComboBox>
</DataTemplate>
</common:DeviceControlTemplateSelector.IntegerTemplate>
<common:DeviceControlTemplateSelector.MultiButtonTemplate>
<DataTemplate>
<ItemsControl ItemsSource="{Binding ValueCollectionList}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<Button x:Name="MyBtn"
Height="40" Content="{Binding Name}"
Tag="{Binding Value}"
cmd:ButtonBaseExtensions.Command="{Binding ElementName=ControlItemList, Path=DataContext.ButtonCommand}"
cmd:ButtonBaseExtensions.CommandParameter="{Binding Value}"/>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</DataTemplate>
</common:DeviceControlTemplateSelector.MultiButtonTemplate>
<Button x:Name="MyBtn"
Height="40" Content="{Binding Name}"
Tag="{Binding Value}"
cmd:ButtonBaseExtensions.Command="{Binding ElementName=ControlItemList, Path=ButtonCommand}"
cmd:ButtonBaseExtensions.CommandParameter="{Binding Value}"/>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
Thanks again everyone for your help!

Answer 1

the best solution i have found so far to deal with this situation is by Dan Wahl where he uses a DataContextProxy.
http://weblogs.asp.net/dwahlin/archive/2009/08/20/creating-a-silverlight-datacontext-proxy-to-simplify-data-binding-in-nested-controls.aspx

Answer 2

Try to change
from
cmd:ButtonBaseExtensions.Command="{Binding ElementName=LayoutRoot, Path=ButtonCommand}"
to
cmd:ButtonBaseExtensions.Command="{Binding ElementName=LayoutRoot, Path=DataContext.ButtonCommand}"
OR
cmd:ButtonBaseExtensions.Command="{Binding ElementName=LayoutRoot.DataContext, Path=ButtonCommand}"

Answer 3

In MVVM messaging is a strong concept for cummunication between ViewModels. You could use PRISM Eventaggregator or the Messenger class of MVVM Light Toolkit. On the button command you can publish a message and subscribe to it in the viewmodel.