Function not imported in Entity Framework

Dear sir/mam,

I want to integrate PostgreSQL database to entity framework in asp.net
using database first approach. but when try to add function then
error occurred:

*Error 6046: Unable to generate function import return type of the store
function.*

I have following configuration:

PostgreSQL 11.6,
npgsql v.4.0.9.0,
EntityFramework6.Npgsql 3.2.1.1,
in .net framework 4.5.2

*My function in postgresql database is :*

CREATE OR REPLACE FUNCTION dbo.EmployeeDetail ()
RETURNS TABLE (
emp_name VARCHAR,
emp_Id UUID
)
AS $$
BEGIN
RETURN QUERY SELECT
"EmployeName",
"EmployeeID"
FROM
dbo.Employee;
END; $$

LANGUAGE 'plpgsql';

Can you pls help! I did more researches but no luck.

Thanks!