Create sum of several matrix questions

Hi there!
I have a matrix question with 5 items and I just want to create some kind of index out of the 6 statements but it does not work. Not even this simple version (later it will be more complex but not even this "easy" version is working).
It should not be that hard but I just don't get it :(
Already tried many variations...

var brandindex= "";
brandindex=
("${q://QID122_1//SelectedAnswer/Recode/1}"-1)+
("${q://QID122_2//SelectedAnswer/Recode/2}"-1)+
("${q://QID122_3//SelectedAnswer/Recode/3}"-1)+
("${q://QID122_4//SelectedAnswer/Recode/4}"-1)+
("${q://QID122_5//SelectedAnswer/Recode/5}"-1)+
("${q://QID122_6//SelectedAnswer/Recode/6}"-1)
Qualtrics.SurveyEngin/ChoiceNumericEntryValuee.setEmbeddedData( "brandindex", brandindex);
The result is -6, so it ignores the Variables
Thank you for your support!!!
Cheers,
Christine