74876 Simple PHP Form Fix

I have some forms that i can add categories to in the admin, they are then displayed in a form so that users can see. Problem is, when info is added to a .txt file, it should be adding like :$category:$cpm:$pop, etc however when i add a secondary category, its outputting the wrong info, i believe this to be a very simple 5 min job, nut i cant see where it needs doing, URGENT