If your Form 1099-R Box 11 is blank and your distribution is from a Roth IRA, it could mean that you will need to determine when you first opened your Roth account so that you can enter that date in the field.
If your distribution is not from a Roth account, then Box 11 will be blank, so you will need to review the code in Box 7 of the Form 1099-R to ensure it matches what you entered when inputting the information, and then review your entries to indicate that it is not a Roth account.