[quote=LAAFTERHOURS]I have the same problem and have the above mentioned “simple fix” screws and tools. The problem is finding the joists which i have been unsuccessful at. I have a pretty good (new) stud finder with deep scan but its impossible to find the joists and this tool mentions that you must screw into the joists to secure the wood planks below the carpet, tightening up the subfloor and eliminating the squeak. Maybe im doing something wrong.[/quote]

I imagine people not having success mostly where two sheets of sub-floor butt together. You probably figured this out already.You know which one is not a butt joint because it has fewer fasteners over the joist as indicated by the stud finder.

The original fasteners should have staggered spacing…one on one sheet then one on another down the line into the joist. If you are averaging the space between these rows of screws your fix screws are going in the gap between sheets. Good chance also the the sub-floor was not fit well in the first place and it’s hard to hit the the joist. Use a thin nail first, hammer it in partially and get a feel for hitting a joist. Then pull it out and sink a screw if you have good wood. Try starting your screws a little wide,with an angle towards the center of the joist, keeping in mind you have two rows of fasteners one for each sheet.