Monotone Images not showing

I have seen some previous posts on this problem, but now answers (that I can find anyway).
I have installed the monotone theme to my site. I followed all the instructions in the readme file, but the images are not showing. They work fine with other themes.
I have just uninstalled and re-installed the whole blog, and still nothing.
You can see a test entry at the moment, but without any image.

https://www.matandmariko/holiday

Image has been uploaded and is at:

https://www.matandmariko.com/holiday/wp-content/uploads/2009/04/img_7034b-300×199.jpg

Please can anyone help. I am new to this, so apologies if the answer is really obvious – but I honestly have searched round for the answer.

Many thanks.
Mat.