Daughter and I have had feral cats and the secret is to take her out of the cage into a small room where she can't get away and hold and pet her, call her by her name hundreds of times until she learns it. Put her back into the cage and repeat above as much as you can. It takes a while but soon she will get attached to you. When you can trust her to not hide, then you can forget the cage. My Daughter had one that spent his 11 years of life petrified of her and the family.