Unable to add dependent value set in assignment descriptive flexfileld

Summary:

Clients requirement is a specfic project list be only visible to the employee dependent on the business unit and department he selects on assignment page.

For example : BU - industry services group , Deparment -Discover finanacial services so now only the first 3 projects should be visible to him.

Here a DFF called as Projects on assignment page is dependent on 2 independent value set that are Business Unit and Department.Have configured a manage common lookup which has the data for projects, Business unit, Department where Project name is in Lookup code, Business unit data is in description and department data is in meaning and 2 independent value set XXOPUS_BU_VS and XXOPUS_DEPT_VS and 1 dependent value set XXOPUS_PROJECT_VS.