@Judy1122
It is always difficult to detect the source of such problem, can be multiple reasons.
Are you using the website or the app ?
Maybe think of:
- Using other Airbnb local website then the one your logged in
- Browser settings to strict
- Neccesary cookies no available
- Bad Internet connection
- Or maybe some error at Airbnb-server ?
At which point in the booking process does the message pop-up ?
Did you try another device to book ?