Can't find it on the Admin menu after installation

Weird, test on 3.7.1 and it works but not at 3.8.

However, it is located below Setting menu actually, if called Advance WQSF.

Yes, I got it to work on another site with 3.7.1, but on aircpce.org it didn’t work on 3.7.1, and now that I’ve changed to 3.8 and reinstalled, it is still invisible. https://aircpce.org/wp-content/uploads/2013/12/ajax-wp-query-search-filter-invisible.png

Maybe it crushed with other plugin? This is really weird, never have this issue before.

Have you turn the debug mode on? If there are errors, then it will displayed on the page and it would be easier for me to diagnose the problem.