Why is my Oracle Group By script not grouping all the employee numbers together?

I want to group by the employee number and the total amounts of sales the employee did. But the employee number is on one table and the unit price for each order is on another table. So i did a join and a group by, but I'm still getting multiple employee numbers and I'm not sure why. Also i replaced any employee number with value Null with 0 thats why I used coalesce.