Photoshop Experimentation.

As a way of experimenting with my idea I decided to do what I initially decided I wouldn't do and use Photoshop to edit existing images with my theme.
Using landscape images found of New Zealand on a Flickr profile I'm fond of - Cuba Gallery, I experimented with the idea of placing the 'cube' in different positions, due to them being photographs and not reality, I was able to put the cube in positions that defied the laws of physics, although I found that the images that did this were not very successful.
As previously stated this was intended only as a means of getting some images together and seeing how they would work which is, as the first two show, not very well.
But why don't they work well?
What are their Flaws?
Can it be easily rectified? If so How?


 I found this to be the most successful image, and believe this to be down to the placing of the square and the fact that it is in a position that could be achieved in real life
The composition of the original image allowed me to place the 'prop'  in a place where the viewer could be drawn into it, conforming to the rule of thirds it is only natural that the eye is drawn to the centre of the piece. This image looks a lot more intended rather than just random placing like the previous images, but this does not detract from my original intention, so considered placement looks like it will come into play when playing about in real life with my future experimental images.