timeline actions not working inside a function HTML Canvas

Hello all thanks for your time

I have a problem calling a timeline action inside a function, the movie clip i use in the function always comes out as undifined.

but when i call the action from within a button function it works as normal.

function reset() {

this.rhpump_mc.gotoAndStop(0);

console.log(2)

this.lhpump_mc.gotoAndPlay(51);

}

then i have a button

this.stop_btn.addEventListener("click", fl_MouseClickHandler.bind(this));

function fl_MouseClickHandler(e)

{

console.log(2)

reset()

}

console comes up with both movie clips undefined

but if i put the code all within the button like this .

this.stop_btn.addEventListener("click", fl_MouseClickHandler.bind(this));

function fl_MouseClickHandler(e)

{

this.rhpump_mc.gotoAndStop(0);

console.log(2)

this.lhpump_mc.gotoAndPlay(51);

}

I get no errors and it all functions normally

I must be doing something wrong .

Thank you for your help

PETER