Does your T3 slip show a negative number? If so which box from the slip is it in?

No, it's a positive number, but the box is 37, i.e. Capital Losses.

I understand that part. What I don't understand is why the software slaps a tax on me as soon as I enter capital gains, but doesn't adjust that tax when I enter capital losses. In other words, if my taxable gains are reduced as a result of my losses so should my tax owed. The software simply keeps calculating the tax based on the gains alone.