Since you are using CheckBox-Groups and not normal CheckBoxes, you will have to work with CheckBox-Groups in a little bit different way.
function manageSum() {
var sum = 0;
if ($w("#checkboxGroup1").checked) {
sum += Number($w("#checkboxGroup1").value);
console.log("Sum0: = ", Number($w("#checkboxGroup1").value)
console.log("Sum1: = ", Number($w("#checkboxGroup1").value[0])
console.log("Sum1: = ", Number($w("#checkboxGroup1").value[1])
console.log("Sum2: = ", sum)
}
else{ }
$w("#text141").text = "" + sum;
}
What are the results in the CONSOLE?
Show a screenshot of console.log