Using child theme - Fatal error

Im using the gridmarket theme - tried to edit the topic but it wont let me.

Hi and loving the theme. Though when using the child theme, and I click a product category, I get the following error: Fatal error: Call to undefined function mp_global_categories_list() in /home1/mysite/public_html/wp-content/themes/gridmarket/mp_category.php on line 24

I have tested with the origional theme ( not the child and it works ). Maybe you forgot something in the child theme?

Edit: forgot to mention, the installation instructions are not clear with installing the child theme, so what I did is move the gridmarket theme out of the themes folder and have placed it in wp-content>themes