You have to have search results on the map before you can apply the buffer to them. That is what the message "There is no result to buffer, please make a graphical or text search first" is trying to tell you.
It works fine if you perform search first. The only problem if user accidentally click "Apply buffer" button then will get the error message. It would be nice to show this message "There is no result to buffer, please make a graphical or text search first".