a!update shows error

The update function takes an input of some kind of data and outputs the same with one index in the data changed.  a!update( data: {1,2,3,4}, index: 2, value: 7) returns {1,7,3,4}.  But you don't put it anywhere.  In reality you're just doing this:

saveInto: {

{1,7,3,4}

}

What does that even mean?  It's just hanging out in space, and Appian isn't told to use it for anything so it just throws it away.  Really, it gives exactly the error message you've gotten.  If you do save function, save( local!myVariable, a!update( data: local!myVariable ....)) , now you're putting {1,7,3,4} somewhere, specifically you're putting it into local!myVariable.

The update function takes an input of some kind of data and outputs the same with one index in the data changed.  a!update( data: {1,2,3,4}, index: 2, value: 7) returns {1,7,3,4}.  But you don't put it anywhere.  In reality you're just doing this:

saveInto: {

{1,7,3,4}

}

What does that even mean?  It's just hanging out in space, and Appian isn't told to use it for anything so it just throws it away.  Really, it gives exactly the error message you've gotten.  If you do save function, save( local!myVariable, a!update( data: local!myVariable ....)) , now you're putting {1,7,3,4} somewhere, specifically you're putting it into local!myVariable.

thank you , will try it