Oracle Forms: Why can't I add a new Type Spec?

I wish to add a Type Spec to a开发者_开发百科n Oracle Form. Unfortunately, this option is disabled in the "New Program Unit" dialog:

Does anyone know how to add a Type Spec to an Oracle Form?

Version of Oracle Forms Builder: Forms [32 Bit] Version 10.1.2.0.2 (Production)

I've never created one with forms but one way to enable the type spec option is: from the Object Navigator expand the database objects node. Then select PL/SQL Stored Program Units now click the create button (so it brings up the dialogue box shown in your screen shot)

However this time the type spec option will be enabled.

Hope this helps.