You have to match exactly the page extensions actions, its page have slightly different groups, also you have to add all of them, and you customize action be the last or be added at the end of new ones. Like for example for Sales Order:
PromotedActionCategories = 'New,Process,Report,Approve,Release,Posting,Prepare,Order,Request Approval,History,Print/Send,Navigate,CustomActionGroup';
Then on the action declare the properties:
Promoted = true;
PromotedCategory = Category13;