Overload resolution failed becuase no accessible ' =' can be called with these arguments

I got this error in SSRS, The value expression for the textrun 'textbox' contain an error [BC30516] Overload resolution failed becuase no accessible ' =' can be called with these arguments

This is the expression that cuased the error
=SUM(SWITCH(Fields!_Age_Range = "13 - 19", Fields!Fact_Invoice_Count.Value))

Does anybody seem to know what is the issue here