Column Object has an error

Can anyone help me with the following please?

This code produces the error below:

Duration from Assigned (wd) = if('Cases'[tpo_layerassigneddate]>0,CALCULATE(
    COUNTROWS('Date2'),
    DATESBETWEEN('Date2'[Date],'Cases'[tpo_layerassigneddate],'Cases'[Closed & Now] +1),'Date'[Is Working Day] = TRUE(),
    ALL('Date2')
))

Is Working Day code = 

Is Working Day = IF('Date2'[DayofWkNumber]>5,0,IF([Public Holiday]>1,0,1))

I converted the Format of Is Working Day to True/False but I'm still getting this error.

Any ideas why?

Thanks