Hi mdsayeed ,

Create 1st DropDownList and Bind datasource to it

1. Drag and Drop DDL from  control menu vailable in right side (make sure allow empty select is checked)
2. On Selecting DDL you will see properties menu on R.H.S., Here goto DataSource and for property name "type" click on browse to add smartobject as datasource to DDL
3. Under use smartobject as datasource make sure below details are added
       SmartobjectValue, DDLSelect Method,  value 
4. Under Show items from the selected SmartObject Add below details
        Display
5. click on OK for Configure DataSource Popup to close it

Same way Create 2st DropDownList and Bind datasource to it.

Goto Rule Section and edit rule as mentioned below

1. for existing rule "When the View executed Initialize" disable 2nd DDL
2. click on Ok  to sabe the changes
3. Create new Rule 

• When "DDL1" is Changed
• then populate "ddl2" list control with data (configure)
• on click configure you will get popup to add input Properties
• just map ID of "DDL2" with ID of "DDL1"