Check to see if you are achieving valid logic levels at the port 0 inputs. The port 2 outputs are not very strong. It could be that your row pullups are too strong. They should be much greater than (5V/1.6mA) ~3K.

Also, if your keyboard is resistive, you may be creating a voltage divider between the row pull-up and the keyboard. That will kill your port 0 voltage level, which must be less than 0.8 volts.