I want to print photos with MK922 it used up small black cartridge but not the large black cartridge

My canon pixma MX922 has a small black cartridge and a larger one.  It is a new printer and I put in the starter ink.  Since I am using it for photos primarily, I bought a pack that came with photo paper, CMYK and a large black cartridge.  I put all of these in and left the starter small black cartridge in.  It has used all of this and none of the large black.  If I take it out, it doesn't work.  I don't understand what the purpose of the large one is, if it is not used and now I won't have any black since the set didn't come with it.