Brian - I guess my disconnect is between your description of the wall and the image itself. Obviously you felt the image works, otherwise you would not have posted it, but the comments (and not just mine) suggest otherwise.
If the image is about the wall, why did you decide that the green at the right your centre of interest? Shouldn't it have been the wall and the protection it offers? Glass embedded on the top of a wall is not something one tends to see in "developed countries", so that might be something worth shooting, if you can line up a shot safely give your mobility limitations.
Take a look at the shots you are getting positive comments on and compare it to images where the results have not been as good. Figure out what works well and what is not working as well for you. Try to use techniques that are working and exclude things that are working less well.
As an example; this is a grab shot of a wall similar to the one that you are describing. It's by no means a particularly good shot, but provides a different way of looking at a wall.