Retirement tax questions

This same thing is happening to me.  I keep entering manually the amount I earned on my 1099R but Turbo Tax is not giving me credit for the federal taxes I already paid.  I feel like this is some kind of glitch in the program.  I have gone over it again and again and reviewed all of the questions but it keeps showing the total taxable amount but does not give me credit for the amount I already paid (that was withheld.)  This is for a state teacher pension plan in Illinois.