Strange search

If I type a text, and press Enter before if shows anyting in the Results window, it shows me a post from the blog.

http://www.jda.es (in search box, I type, for example, “Hi”, and before it shows how many results it has found, it throws me into a post).

Why this happends? If I wait till it shows it, it works properly, but if not that happends.

https://ww.wp.xz.cn/plugins/ajaxy-search-form/