Oracle 10g NVL() not working? I need to create a pivot table of all customers and all products and the price that the customer gets charged but also falling back to a standard customer when the customer has no price set up (the customer 999999 is the standard customer that has a standard price for all products).

I wrote this query;

Select KUST_ADR.KU_NAME As Customer,
  GLAS_DATEN_BASIS.GL_BEZ As Product,
  NVL(OS_PRZU.ZUM2, (Select OS_PRZU.ZUM2 From OS_PRZU
  Where OS_PRZU.IDNR = GLAS_DATEN_BASIS.IDNR And OS_PRZU.KUNR = 999999)) As
  Price
From GLAS_DATEN_BASIS
  Inner Join OS_PRZU On GLAS_DATEN_BASIS.IDNR = OS_PRZU.IDNR
  Inner Join KUST_ADR On KUST_ADR.KU_NR = OS_PRZU.KUNR
Where KUST_ADR.KU_ADR_ART = 0


but still lots of the fields are empty, so NVL() is not working? What am I doing wrong?
Apparently this sub-query does not always return a value:

(Select OS_PRZU.ZUM2 From OS_PRZU
Where OS_PRZU.IDNR = GLAS_DATEN_BASIS.IDNR And OS_PRZU.KUNR = 999999)


meaning that the default customer probably does not have a price for some of the products.

Replace the sub-query with a hard-coded value in order to verify that NVL itself works as expected.