the search does not show any results

You don’t give me the info enough to answer your question.
You should tell me something about the form that you created, eg:

• post type
• taxonomy filters
• meta fields filters.

Make sure you have the correct configuration in search form for the posts you want to search.

Also, try with the default theme to see if it is theme problem, as well as deactivate other plugin to see if it is plugin compatible issue.

POST TYPE: post
Taxonomy Fields: Boolean relationship between the taxonomy queries : AND

I did 4 taxonomy fields: 3 using taxonomy post_tag and 1 using taxonomy category. I put the ID’s I want to exclude, display type: “drop down” for all fields, and “operator: IN” for all fields.

I don′t put any meta fields. (is it necessary?)

I′m using the default theme.

Don’t repeat taxonomy filter in one search form. Instead of using one post_tag for tagging your posts, you should use other custom taxonomy as well.

I tested with only 2 fields, one using taxonomy “post_tag” and the other one using “category”, and still not worked, shows no results. what could be wrong?

Actually, there are many possibilities. You’ll have to test it one by one.

Things that you can do including:

1 .Perhaps the posts doesn’t have the post_tag and category terms?
2. Have you checked the ‘Exclude from search’ ? If you did, please uncheck it.
3. test with one category or post_tag first, to see which taxonomy cause the problem.
4. Switch it to the default theme.
5. Deactivate other plugin that might cause the plugin.