Not too Happy with one of our Furry Kids

We have 3 cats (and a dog). Our cats names are Tiger, Pumpkin and Jasmine. Tiger is 18 1/2 years old and is the grey and black stripped tabby on the right. Pumpkin is 4 years old and is the caleco in the middle. Jasmine is 3 years old and is the grey and black stripped tabby on the left. One of the cats has been pooping in the basement (not in the litter box, but on our new carpet). They keep doing it in the same spot. We don't have furniture in the basement yet, because we need to paint the baseboards and a few other things first. Well, tonight I figured out which cat was doing it. It is Pumpkin. I was downstairs in the office printing out Avon invoices. Dave had just cleaned poop up from the usual spot. When I walked out of the office I saw Pumpkin walking away and there was poop back in that spot. So I put Pumpkin's nose in it and hit her. I don't know if this will work, but it sure is frustrating that she keeps doing this. Their litter box is clean. I guess she is doing it because of Kaitlynn, but Pumpkin gets a lot of attention and plays with Kaitlynn. So needless to say, I am not too happy with Pumpkin right now.