Reference another table in a calculated column

Hi there

I'm trying to be fancy and i've got a date dimension table which has a 'working day' indicator of 1 if it's a working day, and 0 if it's a non-working day.

My Report table has a 'days to complete' column indicating how long it's taken a person to complete a task from the start date.

If the task came in on a non-working day they get 4 days to complete to be inside service level. If the task came in on a working day they get 2 days to complete to be inside service level.

I am trying to build a column to indicate if it's inside or outside of service by using the date dimension table 'working day' indicator. 

I'm getting an error that the experession refers to multiple columns which cannot be converted to a scalar value.

Below is my syntax, can you help me get it right? 

Inside Service = 
    IF ( FILTER ('DimDate', 'DimDate'[WorkingDay] =0 ) && 'Report'[Days to Complete]>=4, 0,
    IF ( FILTER ('DimDate', 'DimDate'[WorkingDay] =1 ) && 'Report'[Days to Complete]>=2, 0,
       1 ) )