Hi,
Here are some things you might want to check;
1. Define Partner Function
you need to maintain the Change Cordinator as Employee, as you see from my screenshot I have 2 additional Partner functions CGMP Team and Business Manager here
2. Define Partner Det. procedure
Your Partner Function 'Change COrdinator' should be part of Partner Functions in Partner Det Procedure. You can refer to my screenshot
And in User Interface Settings;
3. Partner Function used in CRM UI
I used Partner Number 9 and Partner Number 3 ,Partner Number 4 for my 3 level approval procedure
That's all you need.
Regards,
Vivek