Quick test. Why won’t this return the string “Hi”?
CREATE PROC dbo.Testing @Val VARCHAR AS IF @Val = 'One' SELECT 'Hi' AS msg; GO
EXEC dbo.Testing @Val = 'One';
Try it yourself, and answer in the comments. I’ll update this (in comments) in a week or so with the answer, if no one’s gotten it.
And yes, I did this exact thing. You’re never too old to do something like this.