Some of the DS Rom’s I have just don’t show up. That’s confusing. Why those certain games?! Those are my two favorite games!!
They must not match our scanning databases, which are typically based on No-Intro for cartridge-format games. You should still be able to launch them just through ‘load content’ instead of from a playlist.
No-Intro also updates the DS roms frequently. The files that don’t CRC match may require a patch to be applied to verify against No-Intro.
My recommendation would be to verify them with clrmamepro, and use load content as hunterk suggested.