Not able to create attachment section in OAF

I have created a custom oaf page and set all mandatory fields in PageLayout region. Now I am trying to create an attachment section. Done the following steps:

1- created an item and select attachmentTable as the item style and set prompt as Attachments.

2- set the view instance on this item to be the View Object instance created earlier that contains the main record primary key.

3- An entity map is automatically created under attachmentTable item. set the property entity as any random value.(QF_xx)

4- Right click on the entity map and add the primarykeys

5- Right click on the primarykeys and add a primary key