Chinook RV

Greetings all. We just purchased a 2002 Destiny and slowly learning our way around this "beast." I've been working on de-winterizing the rig today. Filled the fresh water tank and faucets work in kitchen and bathroom. However when I flush the toilet it does not refill, pretty much just barely trickles in. The water pump does cycle on but essentially no water at bowl or sprayer. I have tried various settings on the valve behind the bowl but still no work. Please feel free to embarrass me if there is something obvious that I'm missing LOL.
Ellen & Bill Croninger
Henderson, NC

Forgive if this was tried and didn't work but it wasn't mentioned in the post.
On my unit the foot pedal needs to be pulled upward (you can use your foot) to add water to the bowl before or after the flush.