The syntax for 'IN' is incorrect error

Thanks for the suggestions. I need to use IN operator becuase I have a large number of different comparisons. The full expression looks like this:

IF (
    'Unit Information'[Unit Type] IN { "1PAT","1BF" },
    "Frontline Patrol",
    IF (  'Unit Information'[Unit Type]="1SGT",
             "Frontline Admin",
        IF (
            'Unit Information'[Unit Type] IN { "2MAR","2DIVE","2EDU","2K9","2MCB","2OPS","2PSU","2RBU","2TAC","2TMED","3COAST","4MOTO","4RIDE","4RTRF","4SAP","5YED" },
            "Regional Support", "Other Support"
        )
    )
)

I shortened it to validate the syntax. 

I'm using it inside an SSAS tabular model. When I render the object in Power BI Desktop, it gives the error.

I also tried the SWITCH function. But problem with SWITCH is that it only allows a max of 10 values when used with a linked server. This is not DAX limitation but SQL Server linked server limitation.