Use Gripfil adhesive not no nails. Gripfil is a construction adhesive not a DIY glue. It will hold your house together if you want it to. Damp the surface of the tiber slightly by wiping with a damp cloth. Then apply the gripfil in an unbroken bead or beads, Push onto the wall and wiggle about to make good contact. Then pull off the wall. Leave 5 minutes and push back on with another wiggle. Tack a couple of long panel pins or ovals through the timber into the plaster to keep the batten from slipping down and leave to dry for 24 hours. In a weeks time you will see a real life project on DIY Doctor where we have glued up a 8 x 1 inch timber to a window head, then glued plastic facia board to that and fixed THREE roller blinds. We have to say that we only use adhesive when screws cannot be used because of steel lintels or some other reason but this is not because the fixing is stronger its because a few screws are a lot cheaper than a tube of Gripfil.