Error message explanation needed

Question

What does it mean when this code <esri:ArcGISDynamicMapServiceLayer ID="BaseMapLayer"  VisibleLayers="0,1,8"
                     Url="http://maps.pagnet.org/arcgis/rest/services/SchoolSearch2/MapServer" />

produces an error that says "Unable to cast object of type Microsoft.Expression.DesignModel.DocumentModel.DocumentPrimativeNode to Microsoft.Expression.DesignModel.DocumentModel.DocumentCompositeNode? The error is coming from the VisibleLayers property.
Thanks

DonFreeman · Answer

Thanks Morton. This was really bugging me. 🙂

SomeGISGuy · Answer

This is bug in Blend 4 RC. I reported it here: http://connect.microsoft.com/Expression/feedback/details/552430/it-is-not-possible-to-create-a-type-converter-for-ienumerable-int-or-int-that-blend-supports and it was recently marked fixed, so you (hopefully) shouldn't see this when Blend goes final.