Anyone know how to write price level value to an inventory item? Trying to update an Inventory Item Price Level. We are NOT using multi-currency and NOT using qty tiers for pricing, just vanilla, extra price levels. I've figured out how to READ the price level value, but not write back to it.

var PItem = nlapiLoadRecord('inventoryitem',PID);
var PItemWS = PItem.getLineItemMatrixValue('price', 'price', 4, 1);
var WSale = 7.99;

PItem.setLineItemValue('price','price',4,WSale);
PItem.nlapiCommitLineItem('price');