Missing something setting up a button

I've finally started playing with my Espruino, going through a few of the tutorials and trying a few things out.
I'm having trouble replicating the BTN1 functionality on a external/extra button. I've connected a press button between pin C1 and 3.3v and my test code is

function onInit() { 
pinMode(C1, "input");
 }

 function buttonPressWatcher(e) {
    console.log("pressed!" + e.time); 
}

function buttonReleaseWatcher(e) {  
    console.log("Release!" + e.time); 
}

setWatch(buttonPressWatcher, C1, { repeat: true, edge: "rising", debounce:100}); 
//setWatch(buttonReleaseWatcher, C1, { repeat: true, edge: "falling"}); 
setWatch(buttonReleaseWatcher, C1, { repeat: true, edge: "falling", debounce:100}); 

setWatch(buttonPressWatcher, BTN1, { repeat: true, edge: "rising", debounce:100});
//setWatch(buttonReleaseWatcher, BTN1, { repeat: true, edge: "falling"}); 
setWatch(buttonReleaseWatcher, BTN1, { repeat: true, edge: "falling", debounce:100});

A press and release of BTN1 results in the logging of a press and release. A press of the button on C1 only results in the logging of the press.
If I take the debounce parameter off the C1 setwatch command, I get a continual stream of "Release!" log messages.
Any hints as to what I'm missing would be appreciated