I have read the other posts about plugs for fixing to plasterboard and was about to get some Self Drive metal plasterboard fixings. Fortunately I checked out my wall first by drilling a 2mm hole through the plasterboard which is 12.5mm thick. The problem I have is that there is only 12.5mm cavity behind the p/board before I hit 'concrete' or similar. The Self Drive fixings seem to start at around 30mm or more so they won't fit as there is only 25mm from the surface of the plasterboard to the concrete. The spacer battens/studs are not in useable locations. Can anyone suggest another type of fixing please? The curtains and pole will be less than 10kg in total weight and there are 3 supporting brackets which need 3 screws each (arranged in a circle of 12.5mm diameter. The screws are 4mm diameter threads. Help!