So ReShade does not get loaded when you start the game? Did you choose the right API? Possibly it has Direct3D 11 instead of 9? If ReShade gets loaded at least shortly, it will create a log file with the name of its DLL, so for Direct3D 9 it would have d3d9.dll and a log file named "d3d9.log". For Direct3D 10/11 it would be dxgi.dll and dxgi.log, respectively.
Another reason might be that iw4x blocks the loading of unknown DLLs as an anti-cheat measure. Sometimes older versions of ReShade get loaded as they have been presumably whitelisted. Here you can get older versions of ReShade:
www.mediafire.com/folder/8ar1jhh1809cl/ReShade_Repository