search by category

hi every one,
i am using search by category plugin .
Plugin Link
can any one help to me to sort out searching problem with search by category. when user leaver search box blank and select no category it showing this msg
Nothing Found

Sorry, but nothing matched your search criteria. Please try again with some different keywords.
but i want that when user left blank search box it should show all the content how it is possible..

Thanks in advance.