Can't update inventory on an item

I am trying to update the inventory on an item using a Web Service call.
When I try to do so, I get this error back from the call:

You must specify a valid line ID. Please set locationId.

Here is my test code:

RecordRef locationRef = new RecordRef();
locationRef.setInternalId("1");
locationRef.setType(RecordType.location);
InventoryItemLocations updateLocations = new InventoryItemLocations();
updateLocations.setLocationId(locationRef);
updateLocations.setQuantityAvailable(25.0);
InventoryItemLocationsList updateLocationsList = new InventoryItemLocationsList();
updateLocationsList.setLocations(new InventoryItemLocations[] {updateLocations});
InventoryItem updateItem = new InventoryItem();
updateItem.setInternalId("199");
updateItem.setLocationsList(locationsList);
NetsuiteUtil.getInstance().update(updateItem,null, null);

As you can see, I am setting the location ID.

NetsuiteUtil is a utility class I wrote to interface to the Web Service.