Word 2016, table of contents

[toc]

Hey. So I'm writing a paper in word, and I'm using different headings. I have a main heading for each new "part" of the paper, and a heading for subparts of each part. Anyways, the problem comes when I try to use the automatic table of contents. I have used both "heading 1" and "heading 2" on my headings, but out of my 7 headings, only one shows up.. How can I fix this? It's been a problem for a while, and I've tried to open a new document and try again, but it still won't work..