Unable to create Measure

I was creating a measure column using the below code:

Measure = SWITCH(

TRUE(),

[FlagD] = "Red", UNICHAR(128315),

[FlagD] = "Green",UNICHAR(9650),

[FlagD] = "Yellow",UNICHAR(128310),

BLANK()

)

 

It shows me error as:

 

Contrary if i create new column with same code, it is ok. ANy help on this subjetc as i am new to Power BI