Null value in Dashboard Prompt (select list) OBIEE 11.1.1.6

When I migrated RPD and Catalog from OBIEE 11.1.1.5 to 11.1.1.6 (cause of sync AD bug).
Some part in report changed , in dashboard prompt has more 1 choice is Null.
The Null value not exist in my dimension table but it shown in dashboard.

How to solve it? I found the method from http://www.rittmanmead.com/2012/03/obiee-11-1-1-6-new-dashboard-analysis-and-reporting-features/  from Khun Scott reply.

Step that I already test and it work
1. My problem

2. Go to OBI Admin and go to column in Physical layer, deselect Nuulable

3. Result No Null

I don't sure Khun Scott is the same with Scott at Oracle education or not , but thanks for your your reply and thanks for Rittman Mead!

Oracle ODI Tutorial

Oracle ODI Tutorial workable link

Official PDF from Oracle document link
**Getting Started with an ETL Project**
http://docs.oracle.com/cd/E15985_01/doc.10136/getstart/GSETL.pdf

First step for implementation (Online Document)
**ODI11g: Creating an ODI Project and Interface: Exporting a Flat File to a RDBMS Table**
http://www.oracle.com/webfolder/technetwork/tutorials/obe/fmw/odi/odi_11g/odi_project_flatfile-to-table/odi_project_flatfile-to-table.htm