This sounds terrible, but....

I was fortunate to get a gift from everyone who attended. But I hear stories all the time. it's something you will never forget. But don't let it get to you. If they are all from your job, I would assume they all talked to each other and found one wasn't giving a gift so maybe they all decided they would;nt. It's wrong and very tacky, but what can you do. I would cross them off my X-mas list if I were you:)