Cannot convert value '+' of type Text to type True/False

Hello,

This is suposed to be a very simple conditional formula but I am actually stuck. 

Earnings Amount vs LY Variance % Arrow = 
SWITCH (
    TRUE (),
    [Earnings Amount vs LY Variance %] > 0, "+",
    [Earnings Amount vs LY Variance %] < 0, "-",
    BLANK ()
)
    && FORMAT ( [Earnings Amount vs LY Variance %], "0.00%" )