Tier2 Submit validation error due to incorrect CAS number

What do I do if I get a validation error in Tier2 Submit due to an incorrect Chemical Abstracts Service (CAS) number?

Your CAS number should be typed exactly as it appears on the substance's SDS. Review your safety data sheet (SDS) to see if the CAS number was typed incorrectly (for example, a missing digit or two digits typed in the wrong order). If for some reason, your SDS or other sources does not have the CAS number, consider looking up the chemical in the EPA Substance Registry Services, CAMEO Chemicals, or another database to see if you can identify the correct CAS number. If you cannot find the correct CAS number and Tier2 Submit does not require a CAS number, you may leave the field blank.