For those who do some R&D, you are going to detect that if you produce say two approaches in a category and check out to connect with 1 inside A further, it doesn't figure out strategy Except you add self (reference of class). You will also find some cases in https://sap-training-providers12233.izrablog.com/37776378/the-5-second-trick-for-self-adhesive-mini-trunking