My Ereaders cant see series tag

I tried bunch of Ebook readers, and none of it see my books in series order.Actually, it won't even show as series.I am pretty sure I manualy tag my books in series colum.I even have them numbered as series go on, and it makes me mad when I have to google it what books comes next.Did I go somewhere wrong?My format is mobi.

Thanks for help.