select in operator problem

Hi, when I use  this code, it gave empty column

declare @EmployeeID nvarchar(max)=''
set @EmployeeID = '295847284,974026903'
select FirstName, LastName,Title,HireDate,Birthdate,EmailAddress AS Contact 
from dbo.DimEmployee 
where EmployeeNationalIDAlternateKey in( @EmployeeID)

while I replace @EmployeeID with '295847284,974026903',

declare @EmployeeID nvarchar(max)=''
set @EmployeeID = '295847284,974026903'
select FirstName, LastName,Title,HireDate,Birthdate,EmailAddress AS Contact 
from dbo.DimEmployee 
where EmployeeNationalIDAlternateKey in( 295847284,974026903)