Try changing the Content Type drop down menu from the popup and see if your content type exists. If it exists then maybe you need it to be selected by default when you upload a document.
To set it as default you need to change the content type order of the list. You can go to the library settings and in the content type section click on the Change new button order and default content type and set it to number 1. If you you want to do it programatically you can use this blog as a start.