Be sure that you choose the CSA 1099-R type and not just a 1099-R.
The box 2a may or may not be the taxable amount if you are using the simplified method and have a basis in the account.
If you are not using the simplified method and use box 2a then TurbpTax interview will ask you if you want to use box 2a as the taxable amount.
Delete the 1099-R and re-enter.