Firstly you're missing the "extends ..." part, unless you haven't posted that.
Try this anyway
Actor TargetReferenceAlias Property MyAlias Auto Event OnInit() Actor kActor = MyAlias.GetReference() as actor Target = kActor EndEvent
Very often you'll have problems trying to cast different types of objects to eachother, like how you were. So it's best to create the variable first in the correct type (make the Actor variable), then cast that variable to your property. Rather than saying "Create an Actor from this Reference Alias guy and make him an actor in another thing", it's best to put it into stages like "Create an Actor from this Alias guy. Then, when you're done Mr Papyrus, make that actor my other actor".