Invoking a Viewmodel Method From an Event Handler In a Resource Dictionary - wpf

Question

What I'm trying to do is wire up the Completed event of a StoryBoard that's declared in a Resource Dictionary to invoke a method on my viewmodel.
I declared the StoryBoard in a Resource Dictionary because it's used by 5 Styles, also declared in this Resource Dictionary. My Resource Dictionary is declared as below
<ResourceDictionary x:Class="PrimaryAssets"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:pry="clr-namespace:PowderKegSoftware.Artisan.Client.Primary"
xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity">
<BeginStoryboard x:Key="ShowAspect">
<Storyboard TargetProperty="Opacity"
FillBehavior="HoldEnd"
Completed="HandleTransitionCompleted">
<DoubleAnimation To="1"
Duration="0:0:0.4" />
</Storyboard>
</BeginStoryboard>
.............
I added a method to my views code behind called HandleTransitionCompleted which invoked my viewmodel's method but I can't get a reference to my view from this Resource Dictionary.
I tried using a command by making HandelTransitionCompleted a property that holds an ICommand instance and using a command in my StoryBoard like so
<BeginStoryboard x:Key="ShowAspect">
<Storyboard TargetProperty="Opacity"
FillBehavior="HoldEnd">
<i:Interaction.Triggers>
<i:EventTrigger EventName="Completed">
<i:InvokeCommandAction
Command="{Binding Path=HandelTransitionCompleted,
Mode=OneWay}" />
</i:EventTrigger>
</i:Interaction.Triggers>
<DoubleAnimation To="1"
Duration="0:0:0.4" />
</Storyboard>
</BeginStoryboard>
.........
This throws an exception saying "Cannot freeze this Storyboard timeline ....." and after doing some reading I understand why.
Is there a way to get this event handler to invoke the method on my viewmodel.
Any help would be most welcome and thanks in advance.