More subcategories for existing dependent dropdown list - Calc

I am a linux user (Fedora), I was given a .xls made in Windows that had categories and subcategories, the data sheet was arranged so that the first entry in each column was the category, and all the entries below it the subcategories.

The important part in the spreedsheet (Not the same where the data was placed) was that you could choose from a drop-down list a category and then in the cell next to it choose the subcategory from another drop-down list.

My problem is I need to add another new category and subcategories but cant seem to do it if I just add the text the way it is arranged right now. Can choose the new category from the list but when choosing the subcategory #REF appears.

Have read all the entries here and in another forum and they all say the validity check for cell range but cant seem to find a way to make it work. I can make it so that if i choose the cell range of the subcategores then it shows me everything, but dont know how to make it so it only shows the subcategories of the category that was chosen . All i can tell you for sure is that in the Data/Validity for the subcategory drop-down list is in the way of INDIRECTO($previouscell), and the previouscell is the one were you picked the category.

Hope everything was clear enough, I really dont know much about excel or libreoffice calc. I have been busting my head reading and just exploring options and cant seem to figure it out.

Please press Ctrl+F3 and verify that your new category present in list (and add it if necessary)

Thank you! Had found a way to look at that list but couldnt see an add button, with that shortcut i was able to add it! Thank you very much