Dunning Procedure Forms

Hi all

I would like ti know how I assign SAP script forms to dunning texts.

I've copied and modified the form f150_dunn_01. Now I want to assign my modified form to dunning texts. In Transaction FBMP when I click on Dunning texts it takes me to the dunning text screen where I should be able to assign my modified form. But the screen is greyed out and not editable. How do I make it editable?

Thanx in advance.

Will award points.