how do i get my jack russell to poop outside?

by alisa
(Germany)

I have a Jack Russell that is almost a year old and she was doing really well on her potty training, but now she will not poop outside.. We will walk her FOREVER and she will not poop outside, we come in and 2 seconds later she poops.. I have started taking her for more walks and if she does not poop I will lock her in her crate until she poops when I walk her.. How do I get her to only poop outside??