If you just recently received your Son's Social Security Card very recently, the Social Security Administration (SSA) may not have updated this information to the IRS yet. Unfortunately, sometimes it takes a while for the new records to be transferred from SSA to the IRS.
I would suggest double checking his Social Security Number on your tax return while having his actual Social Security Card right in front of you for verification. If you confirm the information on your tax return is correct, you probably just need to give it some more time for the information to be transferred. You can also contact SSA to make sure there are no issues on their end.
