T-SQL (SS2K8) :: Using A Date Comparison In A Case Statement?

I am trying to use a date comparison in a statement using the year statement as well. Here is what I have:

Case [LastHireDate]
When YEAR([LastHireDate]) < Year(@EndYearlyDate) then '12'
When Month([LastHireDate]) = '1' then '12'
When Month([LastHireDate]) = '2' then '11'
When Month([LastHireDate]) = '3' then '10'
When Month([LastHireDate]) = '4' then '9'

[Code] ....

When I am looking at it [LastHireDate] is showing that red line underneath. The < symbol has a red line and @EndYearlyDate has a red line. I can not seem to get them to clear and am, wondering what I am missing. When I execute the error comes up that it does not like the < sign in there.

Here is the full piece that the Case resides in:

Insert _Test
SELECT
EmpNo,
PersonIdNo,
REPLACE(PersonTaxIdNo,'-',''),
LastName,
FirstName,

[code]......