Raycast only works in cartain areas of scene

I am building an RTS style city building game and am havig an issue which I believe is connected to raycasts and the camera. I am using raycasts to determine where on the ground buildings are to be placed, however I cannot place buildings in certain areas towards the top and bottom of my map and I am unsure why. I am using an orthographic camera and if I change the position, or clipping planes of the camers the areas where I am unable to place buildings also changes.

Any help would be appreciated, thanks in advance.

I think its because you dont use layers, check if the camera ray cast is on the all layers.