Fetch From Is not working in Custom Doctype

Hello,
I am creating a new doctype and in that i have linked the Employee field. now when i am trying to fetch the employee name based on the employee linked field, its not showing any fields in the selection list as shown below, however when i tried to fetch any other linked doctype its working fine

Can anyone suggest the solution!
Thanks in Advance

Please check the video (Fetch From - Default Feature: start with 0:55)