use variables in WHERE doesn't work?

[poolman]

If I use a variable the query returns no result.
If I hardcode some value I know is in the table it works 100%.
What is wrong here?
Thanks!

@employee_name			VarChar,
@department_name		VarChar

AS
SET NOCOUNT ON

SELECT DISTINCT
	e.naam as employeeName,
	d.naam as departmentName
FROM
	departments d
	JOIN emp_dep ON d.id=emp_dep.dep_id
	JOIN employees e ON emp_dep.emp_id=e.id
	JOIN hours h ON e.id=h.employee_id
WHERE
	e.naam = @employee_name
 RETURN

[poolman]

Ok, made some progress already. I have this:

ALTER PROCEDURE dbo.spGetTimesheetListing
@employee_name			VarChar(50),
@department_name		VarChar(50)

AS
SET NOCOUNT ON

SELECT DISTINCT
	e.naam as employeeName,
	d.naam as departmentName,
	@employee_name as input_e_naam
FROM
	departments d
	JOIN emp_dep ON d.id=emp_dep.dep_id
	JOIN employees e ON emp_dep.emp_id=e.id
	JOIN hours h ON e.id=h.employee_id
WHERE
	1=1
	SELECT CASE WHEN @employee_name !='' THEN 'AND e.naam = @employee_name' END
	SELECT CASE WHEN @department_name !='' THEN 'AND d.naam = @department_name' END
 RETURN

Now If I use the

SELECT CASE WHEN @employee_name !='' THEN 'AND e.naam = @employee_name' END
SELECT CASE WHEN @department_name !='' THEN 'AND d.naam = @department_name' END

I get all rows of the table. If I use

AND d.naam = @department_name

I get only the rows I need. Looks like the CASE/WHEN construct is
not working...

[NeoPa]

I don't have any SQL server docs with me at home but shouldn't it be SELECT CASE WHERE rather than SELECT CASE WHEN?

[poolman]

thanks, but no. This isn't a sql select statement but an Transact SQL extension og SQL. It's CASE WHEN THEN