Line graph: drill down but show active filter only

[7mon]

Hi everybody,

I try to create a line graph which displays the development of stock, but only the one entry of the dimension which is actively filtered.

To provide some information about the actual stock, a table with a drill down dimension sorted descending by stock quantity is displayed at the left side and a line graph should display it on the right.
If the drill down dimension is used in the line graph, all available entries of the dimension are displayed, such as:

I would prefer to display the one entry which is actively filtered such as:

To display the line graph Iike this, I created a dimension using the following expression:

=if (GetSelectedCount([M.MATERIALNumName_$(vLang)])>0,[M.MATERIALNumName_$(vLang)],
if (GetSelectedCount([MG.MATL_GROUP5_$(vLang)])>0, [MG.MATL_GROUP5_$(vLang)] ,[MG.MATL_GROUP4_$(vLang)]
)) 

Can you come up with a more efficient way of displaying the filtered entry in a dimension only using a drill down dimension?

Many thanks for your help in advance

Simon