I have plasterboard walls with a one inch cavity. I have so far tried toggle fittings which don't fit due the the depth of the cavity and the redidrive fixings which span round when the screws were put in to the extent that the came back out again. The plasterboard is so soft it can't seem to hold anything. I was thinking that I would have to put in gripfill or something like that. I have a load of shelves to put up that have 10 screws per shelf so need to ensure that it is safe enough to hold some heavy books. Help please, I am ready to move as a result of this!