DAX help for calculating revenue impact - MTD Average Price to Trailing 3 Months Average Price

[sanimesa]

I need to show the impact on price changes for each item, for instance current month average price to trailing 3 month average price. 

I created three measures, MTD Average Price, Trailing 3 Months Average Price and the MTD Quantity.

Then a measure for the Price impact;

Price Impact Trailing3 = SUMX(Reporting_JSG_ConsolidatedInvoices, [MTD Quantity]*([MTD Average Unit Price] - [Trailing3 Average Unit Price])) 

This is not showing the expected result - basically it is calculating the [Trailing3 Average Unit Price] as zero in this context. 

What is the correct way to create the desired measure? Any help appreciated. 

Sample data attached below:

https://1drv.ms/u/s!AqfAbaFIezosa2I2Ny9-JQCi4nM

MTD Average Unit Price:  $369.41 

MTD Quantity: 281

Trailing3 Average Unit Price: $536.92

Price Impact Trailing3: $573,133.88 (incorrect)

Expected Correct Result:    ($47,070.31)  (=MTD Quantity*(Trailing3 Average Unit Price - MTD Average Unit Price:)

Thanks.

[mattbrice]

Need to see model design and measures to help.  Or sample table data and desired output.  Not enough info provided to help.

[sanimesa]

@mattbrice  Hi Matt, Posted a sample file and added more explanation.

Thanks.