Running through the initial story mode. Belts on first extractors not working.

[gloomy egret]

I am running through the first story mode parts and built my first two extractors and connected them with belts. However, the belts are not carrying any ore from the extractors.

If I build the belt but not connect it to the smelter, it sometimes works.

Oh. I think this is because I connected the extractors to the smelters, not the refinery. User error.