New fields added to form scenario don't appear for selection in form repository

Hi experts,

I've added 2 new fields to my form scenario but when I edit my FPM form the 2 fields do not show in the repository for selection. If however I create a new FPM form then the 2 fields are there. Is there something I'm missing in order to get the new fields selectable in the existing form?

Thanks in advance,

Chris