That means the the employers EIN on a W-2 does not match the IRS database. Check your W-2 to see if you entered it correctly. If you did, check with the employer to see if they put the correct number on the W-2. If it is correct the the errror might be on the IRS end so the only option will be to print and mail the return with a copy of the W-2 attached.
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**