Eliz Orban and her husband boarded the jet from Denver to Newark with their little girl. The parents were masked up and tried hard to get their daughter to wear the mask, but she wasn't having it. Watch the video ... Eliz's husband pretty much did everything he could ... to no avail.

That's when a flight attendant came up to them and announced they were being booted from the jet. Eliz's husband tried explaining he did his best, and he was more than willing to cover his daughter's face, but the flight attendant wouldn't budge. They had to go.

Now get this ... United wouldn't remove their luggage from the cargo hold, and that included their daughter's car seat. And, on top of that, Eliz says United has permanently banned them from flying.

These are the mixed messages that are driving folks crazy. Governors are keeping pre-schools open because they say small kids don't pose much of a risk, yet this happens. The CDC has recommended children over the age of 2 should wear face masks, but this kid is 2.