This code was disabled by the game programmers.
There are only 2 ways to access this code.
The first way, as seen in this video, is to hex edit the ROM.
As you will see, I simply press the Up button 8 times to turn it on.
The other way is to use the following cheat device code:
Debug Text On
Or, here you can download the hacked ROM which re-enables the code you enter in while paused:
Simply press Up 8 times while paused to turn on/off the code.