The ground behind the retaining wall in my front yard is sinking and I am not sure how to remedy it. I have tried filling it three different times and it just keeps sinking out. I am not sure why it is doing this. When the company installed the wall they did have to move it back a little bit because they put it in the wrong place. I am wondering if having to move the wall had something to do with it sinking out like it is. What would you guys suggest I do to try to fill it and get it to stay solid behind the wall? Thanks in advance.