I recommend verifying that your husband's last name and social security number is listed on your Tax Return exactly as it appears on his actual social security. I suggest locating the actual social security card, not looking at a previous tax return or other documents to verify.
If he has two last names or two middle names, that could be causing the issue. If there are two last names, use the "first" last name. If there are two middle names, use the "second" middle name as the last name (then leave a space and include the last name). Also be sure to include any suffix to the last name like Jr, Sr, III, etc.