MDX count days - since registered (customer) - dynamically

Question

Hi, I have a problem with a MDX statement and I did not find an approach.
We have a customer dimension that includes a date for the registration. We want to know following:
How many days since the registration, but not only for the actual date (today), it must be dynamic.
Example:
Customer A registered on 2011-08-15 (yyyy-mm-dd).
Whenwe choose the time dimension an we take the date 2011-08-20 we want the number 5 because he is registered since 5 days. When we choose 2011-08-25 the result would be 10 etc.
It could be so easily: calculate the difference in days between Registration day and selected day ([Date].[Date].currentmeber????)
Something like: datediff(days, [dim Customer].[Registration Date], [Date].[Date])
But I´m to stupid to translate this easy problem to MDX. Any hints?

Answer 1

EDIT: Fixed it (Forgot the date-dimension on axis 1) THANKS!
Hi dstewartbi,
your code looks not bad. Problem is: Only the actual date is not enough. I need something like currentMember. If I try this:
WITH
MEMBER [Measures].[Days Since Registration] AS
( StrToMember ( '[Dim Date].[Full Date Alternate Key].&[' + [Dim Customer].[Date Of Birth].CurrentMember.MEMBER_NAME + 'T00:00:00]' )
: StrToMember ( '[Dim Date].[Full Date Alternate Key].&[' + [Dim Date].[Full Date Alternate Key].CurrentMember.Member_Name+ 'T00:00:00]' ) ).Count
- 1
I get following error:Cannot convert 'AllT00:00:00' into date-type
If I just use:
WITH
MEMBER [Measures].[Days Since Registration] AS
( StrToMember ( '[Dim Date].[Full Date Alternate Key].&[' + [Dim Customer].[Date Of Birth].CurrentMember.MEMBER_NAME + 'T00:00:00]' )
: [Dim Date].[Full Date Alternate Key].CurrentMember ).Count
- 1
I get the error (in german): "Operanden des Bereich (:) haben unterschiedliche Ebenen, müssen jedoch identisch sein"
Something like Operands have different levels.