Unknow in many-to-many in Adventure works

I create a many-to-many relation in the Adventure works example.

Dim: Sales Reasons <--Fact Internet Sales Reason--> Dim Internet Sales Order <-- Fact Internet Sales

I have set up Unknow visible for Dim Sales reason and Dim Internet Sales Order. In dimension usage, I set up UnknownMember between Dim Sales Reasons and Fact Internet Sales Reason, between Dim Internet Sales Order and factInternet sales reason.

I hope to see, in the cube browser, sales reasons ---> internet sales amount table can show all the internet sales, ie. some internet sales related to actual sales reasons, some related to Unknow sales reasons.

However, I can't get that. I can only see internet sales with sales reasons. the unknown are not shown. but in the grand total, the total amount includes all internet sales including those without sales reasons.

Any idea?

Thanks