Online check-in documentation invalid, but not obvious why

Thank you in advance for any help you can give us.

I was checking in for my husband who is travelling with our infant; once I have entered the passport details for them both and pressed check-in, we get the following message:

"Travel documents info is missing or is invalid. Please ensure all is entered correctly (passport expiry date must be older than arrival date of your whole trip).
Required travel documents for all passengers must be entered."

Both passports are valid for the duration of our journey, I have re-entered the information 6 times. I do not see what is missing or invalid.

I checked myself in for the flight with no problem.

I would be grateful for any advice, I was hoping to get them printed off tonight, before the Ryanair customer service line opens.

I spoke to the helpline this morning, and they were very helpful. Still not clear why the documentation was not accepted, but they entered it for me, and confirmed it, so I could skip that step.

Hi and sorry we could not answer earlier, however we are not directly connected with Ryanair but we try to help( and most are away for Christmas) .... but it seems you did the obvious and we are pleased all turned out well.. enjoy your trip.