Be sure you have the wth at the end, no capitalization.
From Income Tax Withholding - Utah Income Taxes - Utah.gov:
For payer ID: The Utah withholding account number is a 14-character number. The first eleven characters are numeric and the last three are “wth.” Do not enter hyphens. Example: 12345678901wth.
Contact the employer or payer of the income to get the Utah ID number. If there is no state withholding, you can delete the entire state line.