More than one button - how to setup?

Hi Espruinos!

In my application I would like to use four buttons C2, C3, C4 and C5.

The question is, what is the best way to set up these buttons? I tried

function onInit() {
   //Set the buttons to 0
  C2.write(0);
  C3.write(0);
  C4.write(0);
  C5.write(0);
}

setWatch(function() {
  l = l + 1;
}, C5, { repeat: true, edge: "falling", debounce:100});

setWatch(function() {
  m = m + 1;
}, C4, { repeat: true, edge: "falling", debounce:100});

setWatch(function() {
  n = n + 1;
}, C3, { repeat: true, edge: "falling", debounce:100});

setWatch(function() {
  o = o + 1;
}, C2, { repeat: true, edge: "falling", debounce:100});

Each of the buttons is connected to V_bat on the one side and to C2,3,4 or 5 on the other side. But when I press a button (let's say the one connected with C2), the variable "o" does not increase when I press it the first time, when I press it again it jumps from 0 to 2, then it works and jumps from 2 to 3 and so on but with no reproducibly.
I just want to increase by 1 when a button is pressed.

Thanks a lot, Andreas