DataTemplateSelector not getting called for DragablzItemsControl

[amescodes]

i have a DragablzItemsControl where i'm trying to use a DataTemplateSelector but it isn't being called and the SelectTemplate method isn't being hit at all. - the items will just take on the default style with the yellow thumb. am i doing something wrong? any advice appreciated!

<local:PanelItemTemplateSelector x:Key="panelItemTemplateSelector"
                                 ButtonHeaderTemplate="{StaticResource buttonMenuHeaderPanelTemplate}"
                                 ButtonTemplate="{StaticResource buttonLinkPanelTemplate}" />

...

<dragablz:DragablzItemsControl ItemsSource="{Binding PanelItems}"
                               ItemTemplateSelector="{StaticResource panelItemTemplateSelector}"
                               Margin="5">
   <dragablz:DragablzItemsControl.ItemsOrganiser>
      <dragablz:HorizontalOrganiser />
   </dragablz:DragablzItemsControl.ItemsOrganiser>
</dragablz:DragablzItemsControl>