Wordpress - My child theme doesn't work Error: "The parent theme is missing. Please install your parent theme"

There are three things to check:

1 - Is your parent theme complete and what is the exact spelling of the parent theme's name in its style.css. Uppercase and lowercase are important.

2 - Is the child theme directory named parentname-child. It should be in the themes directory, not in a subdirectory of the parent theme.

3 - Does the child theme's style.css have the line Template: parentname in its header. Beware: NOT Template: parentname-child.

Strictly speaking you don't need a functions.php file for your child theme, but you will probably want to load the parent theme's style.css as well. Read more about that here.

The Template Name in the Child Theme Should be Parent theme's Folder name., If you give the Parent theme Name or something else It won't work.

Is your theme "pricerr" provided by 'sitemile' ?

then the template name should be like

Template: PricerrTheme