Wrong RSS url , error

Hi All,
I am new to this forum. My wordpress website is

http://proliferay.com/

I found that for individual blog post the RSS feed URL is not correct. For example the RSS url
http://proliferay.com/liferay-alloy-ui-character-counter/feed/

produces <lastBuildDate></lastBuildDate> error. Is it possible to fix this issue?

Thanks & Regards
Hamidul Islam
http://www.proliferay.com