Back door Roth IRA Form 1040 line 4B

I followed the instructions found at "How do I enter a backdoor Roth IRA conversion?" in the F1 Help.  But when I checked the results of the backdoor Roth IRA conversion (as it says to below) on Form 1040, Line 4B Taxable amount was showing as $8000 instead of zero, as it should have been.   Why ?  What did I possibly enter incorrectly?

 

To check the results of your backdoor Roth IRA conversion, see your Form 1040:

  • Select Forms from the menu.

  • Select Form 1040 from the menu.

  • Use the scroll bar to find:

    • Line 4a IRA Distributions. Your backdoor Roth IRA amount should be listed.

    • Line 4b Taxable amount should be zero, unless you had earnings between the time you contributed to your Traditional IRA and the time you converted it to a Roth IRA.