Check oil tank if full.
Remove bar and chain, clean bar guide groove especially the oil lubrication hole in side of bar at rim sprocket end.
With bar and chain removed, run saw, oil should be pumping out of oil feed hole on side of crankcase chain guide plate. No oil, then maybe a blockage in oil gallery or oil line leading to oil tank. Flush oil tank out and apply a low pressure stream of air to clear lines. Refill oil tank and run saw again checking for flow. It may take a minute for oil to start flow following the cleaning of the oil lines/gallery.
If oil is flowing check that oil hole within bat aligns with outlet on crankcase. You haven't change a the bar recently have you? Check it the correct bar for you saw.
Cheers
onyamichael
February 2013