The gradient is transparent so you will see the edges of the image through the gradient, especially since the image is cut off on the edges.
Try moving the brown color slider on your gradient farther to the right side as this will blend better with the image, you may have to add more blending steps as well. Feather the edges of the image more so as the edges are not so hard.
The feathered edge worked well.
If the background of image that you have underneath the gradient is a uniform color (it appears to be a uniformly white background, as best I can tell), you might also try adding a rectangle the same size as your gradient below both the image and the gradient, and fill it with white (or whatever the specific background color of your image is). This will only work if you have a uniform background color around the edges of your image, but it looks like in your example that it might work. (see attached)