Why does my student's passcode tell him it's invalid?

[SpitWad]

My student's parent logged in as normal for his lesson using the same Meeting ID and Passcode that she has always had.  This time it wouldn't work.  When she entered the Passcode, Zoom said it was invalid.  We checked and double checked the passcode and Meeting ID.  She logged out, turned off her computer and logged in again.  Same answer.  I logged out and signed out and back in. No change.  It is a puzzle.  What could be the problem?

[RN]

Hi @SpitWad welcome to Zoom Community! As the host, were you using your Personal Meeting ID or randomly generated ID with your passcode? For example, when you go to https://zoom.us/meeting/schedule and schedule a meeting, you will see the following options, I would ensure that the Passcode is associated with the correct Meeting ID or Personal Meeting ID, as they differ. 

As the host of the meeting, check if the meeting information on the meetings page in the Zoom web portal is correct.