DoubleAnimation Crashes XAMLPad (MayCTP)

Has anyone experienced a crash with XAMLPad (I have not tried creating a complete app yet) where by if I have to following:

<settertimeline path="(MenuItem.Width)" name="Timeline"><doubleanimation autoreverse="True" duration="0:0:0.5" to="150" from="100"></settertimeline>

And I remove the "From" Attribute it causes XAMLPad to crash.

<settertimeline path="(MenuItem.Width)" name="Timeline"><doubleanimation autoreverse="True" duration="0:0:0.5" to="150"></settertimeline>

This timeline is used to do a basic animation of the width on a menu item. I am not including the "From" attribute because I want the default value of the MenuItem's width to be the start value. Is this the correct thing to do? Some examples that I have seen say this is possible.

Context: The Timeline is within a Style on HeaderTemplates DataTemplate Element (because I am cusom drawing the control)

Example XAML can be found at http://www.kinlan.co.uk/sample_sources/XAMLAnimationCrash.xaml