error 0xE0040200 when browse a cube

I am using AS 2005 + SP2.

I got error 0xE0040200 when browse a cube with a calculation member for a dimension, the calculation is defined like the following.

iif([Time].[Calendar].currentmember.prevmember is null or
([TimeSeries].[Period].&[1], [Time].[Calendar].currentmember.prevmember) = 0, null, ROUND(((([TimeSeries].[Period].&[1],
[Time].[Calendar].currentmember) -
([TimeSeries].[Period].&[1], [Time].[Calendar].currentmember.prevmember))/([TimeSeries].[Period].&[1], [Time].[Calendar].currentmember.prevmember)),4))'

I think the problem is around "([TimeSeries].[Period].&[1], [Time].[Calendar].currentmember.prevmember) = 0", because when I change the "=0" to "is null", the error disappears.

Can anyone know why the "=0" won't work? BTW, the same calculation works well in AS 2000.

Thanks

It seems that it is a bug of cube browser in AS 2005.

When I browse the cube in Excel with AS 9.0 OLE DB provider, everything is fine.

has anyone experienced the same?

Thanks
Michael