Toilet issue

[Shellbell]

For some reason waste isn't getting to the black water tank. Something seems to be blocking it like a valve? Any idea what the problem is?

[Martian]

Is that a two toilet unit? If so you may have two black tanks.

[JRTJH]

Welcome to the forum. What RV (brand, year, model/floorplan) ???

Keystone doesn't market a "Forrest" RV, so I can't provide any information on black tank configuration or potential problems.

If you'd post the information about your specific trailer, we can likely give you some advice/information on what you're experiencing.