I'm not entirely sure I understand your problem, but I'll try to answer two different scenarios. Every 2001 Airstream should have a Black Tank - for waste from the toilet, a Gray Tank - for sink water, and a white water tank - clean water which can be used for all purposes whenever there is no water line hooked up (such as using the toilet while taking a break on a trip, or deep woods camping without hookups).
Both the gray and black tanks have "gates" to a common drain. The black tank particularly should always have the gate closed (Holding the water) until the person camping wants to drain the tank. If the gate is open all the time, solids form "the black hills" and liquids go down the drain hose "slinky". When the black tank is full or starting to get smelly, it's normal to drain it by going to the roadside, having a drain hose of some type hooked up, and pulling a lever to open the black tank gate. What can go wrong?
- the gate handle can break loose from the gage, you pull and there's no resistance... the gate can't move. This is fixed by (YUCK) disassembling the drain piping and installing a new gate. In most campgrounds someone with a "honey wagon" can pump the black tank out by inserting a hose down the toilet. There are a few other ways to empty the tank before trying to replace the gate - use the search function for details IF this is what you're experiencing
- you DID leave the gate open and now you have a massive clog - IF you can get the gate closed successfully, add warm water and RID-X or some other "digester chemical" to the black tank via the toilet - let it sit for a couple of days and try to drain it - some of these clogs take several applications to dissolve.
- you had a "guest" who didn't know that there are "disposable" hygiene products that should NEVER go into an RV Tank. And now you have sanitary napkins, or tampons or disposable diapers clogging the hell out of the tank. I've seen people dump full ashtrays down a regular toilet - that's bad but much worse with an RV toilet. (Got a LONG pair of tweezers? or do you want to call someone and pay them to get the tank clear again.)
- if what you mean is that the stuff in the bowl no longer goes down even though you step on the lever and the flapper opens... then the tank is filled to overflowing and needs to be emptied into a sewer hookup.
More details would be handy.