Why does MDX sometimes return Missing when using both NON EMPTY and FILTER?

Hi,

I noticed something odd when running MDX statements against SAP BW.

For some cubes, for certain characteristics, when I use both NON EMPTY and FILTER empty data comes back.

For example:

SELECT NON EMPTY  FILTER ({.....} * {....} * ..... * {...}).Current <> 0) DIMENSION PROPERTIES MEMBER_UNIQUE_NAME  ON ROWS FROM [$CUBE]

returns some empty cells. Notice that I use the FILTER to remove the cells that are 0.

When I  use this MDX (without the 0 removal):

SELECT NON EMPTY {.....} * {.......} * .... * {....} (DIMENSION PROPERTIES MEMBER_UNIQUE_NAME  ON ROWS FROM [$CUBE]

I get no empty cells back.

Obviously, I expect and want to get NO EMPTY CELLS back in both cases, but it seems that when I add FILTER some empties get returned. Does anyone know why?

Thanks!