pb with adding image in slider

I probably do not understand well how to add an image in the slider. I have 3 images and want to add a fourth. I add it in the media library, create a post and add the post id in the slider parameters.
This fourth image do not display. What I a doing wrong ?
Pierre

Hi Pierre,

I hope you are well today and thank you for your question.

I add it in the media library, create a post and add the post id in the slider parameters.

You should also set that image as a featured image of the created post as described on the following pages.

http://freewptp.com/tutorials/how-to-set-featured-image-or-post-thumbnail-in-wordpress/

Best Regards,
Movin