You mean Form 1099-R (not 1099-B).
The zero in box 2a indicates that this Form 1099-R is reporting a direct rollover to a traditional IRA, not to a Roth IRA. Unless the distribution was first rolled over to a traditional IRA and the traditional IRA was later converted to a Roth IRA in a separately reportable transaction, you need to contact the 401(k) plan and request that they correct your Form 1099-R to show in box 2a a taxable amount of $15,287.25, the difference between the $17,004.94 in box 1 and the $1717.69 in box 5.
