Triggers: counting rows in a bridge table after INSERT

I'm using a trigger in order to make a Statistic Table. I have this many-to-many relationship where I have an Order that can have multiple Product's and viceversa. So after an INSERT on Order, using JPA, new rows are automatically inserted in the bridge table Order_Products. When in the Trigger I use

SET @numOfOPs = (
        SELECT COUNT(IDOrder) 
        FROM Order_Product 
        WHERE IDOrder = NEW.ID)

on new entries, the count on Order_Procut seems to return 0 (or the value before the insert on Order). Here the signature of the Trigger:

CREATE TRIGGER Order_AFTER_INSERT 
    AFTER INSERT ON Order 
    FOR EACH ROW

What could be the problem? I will add additional information if needed.