Is it possible to return "-" or string to replace (blank) instead of 0 in Column Chart

I try to replace the blank values in Y-axis with "-" or any string. But with Clustered column chart, it allow me to only use 0 or number.

The question is, Is it possible to use string instead of number in this case ? Thank you in advance.

Here is a Dax:

CalMeasure: Sale Trend LY = 
var ly = CALCULATE(SUM(FACT_STORE_SALES[PURCHASE_VALUE_BEFORE_TAX]),
DATEADD(DIM_DATE[DATE_CD],-1,YEAR))
return IF(OR(ly=0,ISBLANK(ly)),0,ly)

The expectation (wanted to return string):

return IF(OR(ly=0, ISBLANK(ly))," - ",ly)