Thanks for replying. I went back and tried again with the same result. Then I tried the xxx-xx-xxxx format since that is what US SINS are in. Didn't work, it said use the xxx-xxx-xxx format. Tried again, didn't work.
I always change one digit in my social because I don't want to be a victim of identity theft. I was taught decades ago never to give it out except for employment and this is not employment, it is being an independent contractor.
But just to see if it worked I did put in my correct social and it went through.
So I give them marks for knowing what they are doing. No one else has ever rejected a fake one.