i just bought a new headset... this one to be exact

https://www.bikemannetwork.com/biking/p/COMPHS1T/HD1001

anyway, got it, came packaged like it's brand new, wrapped up in the box and everything, take it out, press all the races, grease the bearings, put the fork on, screw the adjustable race on (i think my terminology is all correct) and everything fits fine, then i go to put on the lock nut and the threads are too big! it just slides on and off of the fork, not completely, since it always has the top part that stops on top of the fork, but the threads don't grab at all! how is it that the race would work and the lock nut wouldn't? do you think maybe i got a 27.0 locknut instead of the 26.4? that's odd that i would get the wrong part in the package instead of just being shipped the wrong headset (the box is labelled 26.4) help!

oh, and i will be calling them tomorrow, just want to be as knowledgable as i can.

The 26.4 is the crown race diameter, not the locknut size. Sounds like there was a 1-1/8" locknut in with your 1" headset.

it's not big enough to be 1 1/8" i'm pretty sure