2002 Hyundai Sonata Door locks

My remote will not lock the doors anymore.
This started happening a couple weeks ago but eventually the remote would work after hitting the button several times.
As of yesterday it will not work at all.
The button for the trunk lock works. When I hit the button for unlocking the doors the lights flash as they normally do, but thats all.
I tried the spare remote but had the same results.
Also tried replacing the batteries in the remotes but no luck.
Is there some kind of module that went bad and how do I repair or replace this ?

Welcome to this forum, Lynkel

Can it be that there is some kind of obstruction on the locks itself that keeps from locking the doors with your RC?

I am certain nothing is obstructing yhe door locks.As Isaid in the post they would work intermittantly but then they quit altogether.

No I meant something obstructing for the remote control to read the lock.

I'm sorry I can give so little help re. this. I had the same problem once with a quite different subject although the same basic thought:

my remote control did perform its functions on everything I wanted it to do on my tv, except for one... It was real puzzling and in the end I just received a new remote control from the cable company because they neither could track back what exactly was the problem....