First thank you for reply and your help. Now that problem with vertical line is resolved, but the images are still not showing. I did tried all the possible steps to resolve this ”Sorry there has been a problem with your feed” error, by reading all the topics here, but still with no luck.
I also installed fresh wordpress on my test server just to test this plugin, but still the same error. And I was using the default wordpress template in case that there is some bigger conflict with the template on the mentioned page.
Literally have no idea why this error…