@Test()
public void testNullEntryAddDelete() {

	final SizeValue size = newSize(10);
	final PriceValue priceStep = newPrice(25, -2);
	final UniBook book = new UniBook(Instrument.NULL, 
			Book.Type.COMBINED, size, priceStep);
	UniBookResult result;
	result = book.make(null);
	assertEquals(result, ERROR);
	result = book.make(null);
	assertEquals(result, ERROR);
}