Variable not working

Hi,

I have inherited a data model that has dozens of Ages Banding calculations that I want to simplify using Variables. Is this possible on the code below? Please not the error message below.

Age Profile (Creation Months) = 

VAR Age_Profile = 'Cases'[Case Length (Adj)]
RETURN
SWITCH(
    Age_Profile < 90 , " 0-3 Months",
    Age_Profile < 180, " 3-6 Months",
    Age_Profile < 270, " 6-9 Months", 
    Age_Profile < 365, " 9-12 Months", 
            "12+ Months"
)

Thanks,