I have isolated where the squeak is coming from and drove in a bunch of screws in.
The screws had no effect at all!
The only thing that has worked so far is when I have someone walking on the floor and me pushing up on the joist wish all the force I can muster!
Pushing up on the one joist stops the squeak totally.
I looked between the joinst and the subfloor for a place to shim but their bonded with no space seperating them.

Heres the scenerio
when I bounce on the subfloor between the problem joist and its oppsing joist to its right , I get the loudest bounce and squeak, when I go the left side between the joist its more mild.


What should I do next ,steel bridges between the joists even though there are wood ones already there,put up a cleat, sister joist?


zim

Wood blocking in between the joists should help....and sistering in a joist is easy enough with some bolts, washers, and nails if you need to go that far.

Don't assume the floor joist and the subfloor are the only wood elements that can cause the squeak. I had a squeak between floors that was caused by the cross brace being cracked. I had to cut my floor out to solve it. Yours looks much easier - you have access. See that brace in your picture - suspect it! If it is lose or cracked it will squeak as the floor joist moves.