Deductions & credits

I have a question concerning errors that I am getting  on form 6252.

I sold a rental property in 2006 and, over the years, I have been receiving installment payments.

This year TT is giving me errors on form 6252, column 5 looking for "Selling price including mortgages and other debts...." and column 8 looking for "Cost or other basis of property sold."

I have looked for these amount in 2018 TT returns and these fields are blank.

Part I - Gross profit and contract price, for 2019, it asks to "Complete this part for all years of the installment agreement" while the previous years it asked  "complete this part for the year of sale only".

Please advise. I don't know where I can get that info.

Thank you!!!