Wiring a 2-wire outlet into a 3-wire receptacle?
Look at the side of the original outlet the connecting tab is probably broken on the hot side. If you don't mind not having a switched outlet I would cap the red and you should be fine. Normaly the red is the switched connection but not always. If using the black the outlet is still controlled cap the black and connect the red to the outlet and you would be good to go.