Calculated member for the current month

[winner]

Hi,

I am trying to create Calculated Member for the current month
as below
WITH MEMBER [Measures].[currentMonth] as
{[Measures].[SESSION Count]}
select
{[Measures].[SESSION Count]} ON COLUMNS
from Ecgkpi where StrToMember("[Time].[Month].["+ Format(now(), "yyyy/
MM") + "]") .

When I run this as MDX query in Mgmt studio it is giving the count ,
but when I am trying create the new Calculated Member I am getting the
error as the script contains the statement which is not allowed.

Can any one throw whether the above one is correct or not?

Thanks