How do You deposit Ag Layer? You should pay attention that metal (sputtered or whatever) is not sitting on The sides of your sample but only on the top. You can try mechanically remove all layers from sides to be sure that there are no short circuit. The other reason could be that spin coated layers form poor quality island films and metal goes in between.

Thank you. I did clean the sides after deposition, but still did not work. Probably have to cover the sides.

It is true that spin coated films have poor quality. Is there a way to form a film that could avoid this problem?

Short circuit means there are metal bridges connecting the top and bottom electrodes. If you use thermal evaporator, deposit metal at a very slow rate.