Selling problems and buyer contact

[jopap-4276]

We are trying to invoice the buyer of our basketball card.  We have put in the correct postage and we get a blue highlight saying to verify postage amount to the buyers address in USA.  Then we get a red highlight saying problems with the buyers account.  We click on contact buyer but then we get problems with the buyers account again.  I am presuming that the buyer hasn't set up his end properly or could it be a scam.

Thanks