What is happening to my grass?

I’m normally a lurker, but today I need help with my grass. We have worked hard to keep the grass looking nice and green. However, there is one spot that keeps giving us a hard time and no matter what we do, the grass seems to die in that only spot. Recently it has started to spread and I’m ready to scream. Our grass is St. Augustine and the spot is located at the corner of the house right next to the sidewalk. It is the only spot of the house were the grass looks dead. We have no problems in the rest of the house.


As you can see we cleaned out the dead grass and put new one; now the new grass is dead. I’m running out of ideas of what could be causing this. Please help me I can’t afford a professional service at the moment, but I’m afraid that it will be the only solution.