Formula help: adding up mileage fields then multiplying by .58 cent reimbursement rate.

It woked - then when I saved .pdf it was lost when I reopened it.  Then it would only work in some fields an not others.  Now it won't work at all.

// Get first field value, as a number

var v1 = +getField("MileagemilesRow1").value;

// Get second field value, as a number

var v2 = +getField("MileagemilesRow2").value;

// Get third field value, as a number

var v3 = +getField("MileagemilesRow3").value;

// Get fourth field value, as a number

var v4 = +getField("MileagemilesRow4").value;

// Get first field value, as a number

var v5 = +getField("MileagemilesRow5").value;

// Calculate and set this field's value to the result

event.value = .58 * (v1 + v5);