Compare Previous Year by Fiscal Week

Hi there,

I'm looking to compare this year's sales to last years sales, but based on Fiscal Week.

When I use a Measure called "Sales LY" - certain weeks are empty (even though they have data - double checked)

Sales LY = CALCULATE( [Total Production], DATEADD( Dates[Date], -1, YEAR ) )

I've attached a picture of the data.

As you can see from the table on the right - There is data for the period for the fiscal week for each fiscal year... but it doesn't populate when using the Sales LY calculation - I'm sure it has something to do with how it's being calculated.

 

Please help.

 

 

//bijan