Problem with costum group

[backhandx]

 Hi all,
Hi all,
I meet some strange behaviour in Report studio with dimensional costum group.

Actually, I have 3 members from the same level A, B and C.

In a crosstab, I put the 3 members in the column and when executing the report I can see all of them.

Now, I merge A and B member in a costum group (let's call it D column) And I put the D and C in the column of the crosstab. Now when excuting I can only see the C member in the columns of the crosstab but not the D custom group.

I want to know why does this happen?