Can't insert coded field into collection

@givemeawhisky thank you so much for your help so far!
I totally get what you mean, but I still can’t get it to work!

I have changed to field type in the DB to Text, and this is the function now:
export function sumRevenueAmount (){
var total = 0

total = ( 
    Number($w('#inputRevenueItem1Amount').value)+ 
    Number($w('#inputRevenueItem2Amount').value)+ 
    Number($w('#inputRevenueItem3Amount').value)+ 
    Number($w('#inputRevenueItem4Amount').value)+ 
    Number($w('#inputRevenueItem5Amount').value)+ 

    Number($w('#inputRevenueItemAAmount').value)+ 
    Number($w('#inputRevenueItemBAmount').value)+ 
    Number($w('#inputRevenueItemCAmount').value)+ 
    Number($w('#inputRevenueItemDAmount').value)+ 
    Number($w('#inputRevenueItemEAmount').value)+ 
    Number($w('#inputRevenueItemFAmount').value)+ 
    Number($w('#inputRevenueItemGAmount').value)+ 
    Number($w('#inputRevenueItemHAmount').value)+ 
    Number($w('#inputRevenueItemIAmount').value) 
); 
$w('#inputRevenueItemTotalAmount').value = total.toString(); 

}