PLEASE HELP with scaling in AS

hi, i’m using this code to for a button to make a MC “kids1” gradually scale to 300%, in 5% increments, but it only scales it 5% then stop, does anyone know how to make this function repeat until _yscale=300?

  	Code:
[left]on (release) {
if (_root.kids1._yscale<300) {
	_root.kids1._yscale+= +5;
}

}[/left]

any help would be great, thanks in advance!