4 wheel drive wont engage on 2005 GMC Sierra 1500

I just bought this truck a few months ago and got it stuck in a field the other day in 2 wheel, I pushed the 4 wheel button and just heard a grinding noise and the 4 wheel didnt engage. after a few more tries it finally went in and I got out...any suggestions?

Asked by for the 2005 GMC Sierra 1500
the acuator in the front differential amy be the problem. have it checked at a shop for engagement and get a bid for repairs.