Your bank routing number is a 9-digit number. 

Usually it is verified at the bottom left of your check.  However, these days, many of us do not use checks. 

Your bank customer service can verify the correct routing number.

One more thing, sometimes Credit Unions and some Banks have a routing number especially set up for electronic payments or they use what is called a Correspondent Bank.  A Correspondent Bank is an intermediary Bank between the Federal Reserve and your Bank. 

If you keep getting the error, contact your bank to verify the information.