I recently adopted a 7-year-old Yorkie that never lived in a house. It will go for weeks and then make a mistake on the white rug. What can we do?

I have an adorable 7-year old Yorkie named Sassy. I got her from a disreputable breeder when she was 6-years old - she was about to be put down. I saw the makeshift kennel where she was kept - it is obvious she spent the first six years of her life there. He never even bothered to name her. She has adapted well to her new surroundings BUT, she is not house-trained yet. She has been thoroughly checked out by a vet.

I am using a crate to train her - which she has pottied/pooped in. We are on her third crate. She does know the commands to potty and poop - though often I have to force her to poop - by saying it over and over and over again. She'll go for weeks without any problems - then in one heartbreaking - I thought she had it - not on my light carpet - moment, she will potty or poop. I am using your training suggestion for getting her to bark when she has to go out. She knows the bark command and does it to perfection when she wants a treat or out of her crate. But, she is still not barking to let me know she has to go out. Any other suggestions you can give would be greatly appreciated.

Thanks,
Angela & Sassy