Calculate overhead in kke1

Dear Team,

We are going to KKE1 giving base planning object :test1, base unit of measure : ea and specifying the company code , plant and name and enter.

After that system system will show costing variant as pg and click on enter.

There is option called calculate overhead which is disabled. Why is it if yes how to enable calculate overhead ?

Coming to Costing Items - Basic View

There is category option column where in there are options mentioned below.

B Base Planning Object E Internal Activity F External Activity L Subcontracting M Material N Service O Arithmetical Operation P Process (Manual) S Total T Text Item V Variable Item

If we want to create new option what is the path/t.code?

Kindly request to suggest.

Thanks & Regards,

Babu