Yes your retirement pension should be on line 5a and 5b. Did you enter it as a W-2 instead of entering it as a 1099R? Click edit by the W-2 information you entered and see if you put it there by mistake somehow.
To enter your retirement income, Go to Federal> Wages and Income>Retirement Plans and Social Security>IRA 401 k) Pension Plan Withdrawals to enter your 1099R.