Appointment Items triggers

[Josh]

Hi I am trying to change the background color of an appointment based on its current state. I am holding the current state in a custom appointment and trying to use a datatrigger to update the background color. I know that the data is being changed but it is never reflected on the gui.

<Style x:Key="EventBase" TargetType="telerik:AppointmentItem">
        <Setter Property="VerticalAlignment" Value="top"/>
        <Setter Property="Height" Value="22"/>
        <Setter Property="Foreground" Value="White"></Setter>
    </Style>

 <Style x:Key="RuntimePhaseDefination" TargetType="telerik:AppointmentItem"  BasedOn="{StaticResource EventBase}">
        <Setter Property="Background" Value="Gray"></Setter>
        <Style.Triggers>
            <DataTrigger Binding="{Binding IsSuccessfullyCompleted,Mode=TwoWay}" Value="True">
                <Setter Property="Background" Value="Green"></Setter>
            </DataTrigger>
        </Style.Triggers>
    </Style>

Can this be done with an appointment? I have also tried binding the IsSuccessfullyCompleted to the background and using a converter but still get no results on the gui.