Retirement tax questions

THanks - this is VERY CONFUSING as TurboTax asks me for my W-2 information.  That's good.  BUT THEN in the deductions section - it asks how much my wife and I contributed to a 401k - without stating that if that amount is already entered in the W2 - DO NOT enter it again in deductions.  Your answer clarified this - and TurboTax should fix the deductions section to check if the W2 has a 401k, then warn us not to reenter that amount.