MAME32 Plus compile not affected by change to driver.h

[Gradius]

I'm compiling my own build over MAME32 Plus for personal use. I have successfuly compiled it and everything works fine. However, one of the changes I usually do, doesn't seem to work here. This change is made to driver.h

I change this line:
machine->frames_per_second = (rate);

with this other:
machine->frames_per_second = ((rate) >= 50) ? 60 : (rate);

That works with the official MAME32, which I also compile with this modification. It makes all games with a refresh rate between 50 and 60 automatically run at 60hz (same result as with the old SmoothMAME drivers).

Could you explain why it doesn't work here? Can you figure out way to achieve this? I got no errors during the compilation, but those games keep on running at threir original refresh rates instead than forced to 60hz.