But lets go back a step. What happens when you connect just the backlight, the power, and the contrast (pins 15, 16, 1, 2, and 3)?
Did this, when I put the contrast all the way up only the top row changes contrast. The bottom one doesn't.
Back one more step - are you using a resistor in series with either backlight lead?
I am not using a resister in series with either of the backlight lead, is this needed?