Derive Columns From Cube Member?

I have a cube that I read in a data flow section using OLE DB. To get this to work I had to do an ad hoc query through a sql server database ( this is problem that is described in post 219068).
So I now have the data and I want to derive new columns based on that data using an if statement:

if ( ISNULL(" [Facility].[REGION].[NATCODE].[MEMBER_CAPTION] " ) comptype = "NAT" else comptype = "REG"
comptype is the new derived column I am creating.

But when I try to save this I get an error: The expression might contain an invalid token, an incomplete token, or an invalid element. It might not be well-formed, or might be missing part of a requred element such as parenthesis

I selected the cube element from the columns list in derived element, when it initially put it in it looked like:

[[Facility].[REGION].[NATCODE].[MEMBER_CAPTION] ]
and gave error:

The token "[" was not recognized. The expression cannot be parsed because it contains invalid elements at the location specified.

Below is the statement I use to get data back from AS
select * from openrowset('MSOLAP', 'DATASOURCE=local; Initial Catalog=Patient Demographics 2005;',
'with member [Measures].[TimeDisplayName] as [Calendar].CurrentMember.Name
SELECT NON EMPTY { [Measures].[TimeDisplayName],[Measures].[Case Count],
[Measures].[A100 Bathing],[Measures].[A100 Bed Chair Wheelchair],
[Measures].[A100 Bladder],[Measures].[A100 Bowel],
[Measures].[A100 Dressing Lower],[Measures].[A100 Dressing Upper],
[Measures].[A100 Eating],[Measures].[A100 Grooming],
[Measures].[A100 Stairs],[Measures].[A100 Toilet],
[Measures].[A100 Toileting],[Measures].[A100 Tub Shower],
[Measures].[A100 Walk Wheelchair],[Measures].[A200 Comprehension],
[Measures].[A200 Expression],[Measures].[A200 Interaction],
[Measures].[A200 Memory],[Measures].[A200 Problem Solving],
[Measures].[D100 Bathing],[Measures].[D100 Bed Chair Wheelchair],
[Measures].[D100 Bladder],[Measures].[D100 Bowel],
[Measures].[D100 Dressing Lower],[Measures].[D100 Dressing Upper],
[Measures].[D100 Eating],[Measures].[D100 Grooming],
[Measures].[D100 Stairs],[Measures].[D100 Toilet],
[Measures].[D100 Toileting],[Measures].[D100 Tub Shower],
[Measures].[D100 Walk Wheelchair],[Measures].[D200 Comprehension],
[Measures].[D200 Expression],[Measures].[D200 Interaction],
[Measures].[D200 Memory],[Measures].[D200 Problem Solving] } ON COLUMNS,
({[Facility].[REGION].[NATCODE], [Facility].[REGION].[REGCODE]} *
[RIC].[CMGGRPCD].ALLMEMBERS ) ON ROWS FROM [CMG Demographics]
WHERE [Calendar].[Quarter 2 (2007)]')

So can some one help me on how I can do this derived colum.