Custom Rendering Template for Content Type is not working

Hi All,

Created an Content Type from "Item" Content Type and associated a "Custom Form" and it worked fine. Now the custom Content Type inherits from another custom content type which inturn inherits from Item Content Type. Now the custom form is not displaying, it only displays "ListForm" not my "CustomForm".

Using SharePoint Server Object Model , checked the "EditFormTemplateName" of the Content Type and it shows my "CustomForm".

When my custom Content Type directly inherits from "Item" it works fine. After changing the hierarychy(Content Type A -> Content Type Base -> Item) the custom form not displayed.

 Is Content Type hierarchy is the issue

Please provide your thoughts.

Thanks,

Prakash