Retirement tax questions

I have a former employer pension distribution reported on 1099-R. I filled all data asked. Now TurboTax shows Form 4852 questions. On line 4, it checked box "I have been unable to obtain 1099-R". It can't be unchecked. Why it assumes this and wants to substitute 1099-R with form 4852?  This form asks questions like "how did you determine the amounts in lines 7 (W-2 related) and 8 above", "explain your efforts to obtain form W-2, form 1099-R.....". I received 1099-R in mail, I don't have W-2 at all.  It doesn't seem right? How may I accomplish this?