Multiple tier rollup

In the example below, I have created a calculated column "Profit Per Unit" using the following expression:

Profit Per Unit = Divide('Titan_DMS qryNVunitsandGP'[Profit],('Titan_DMS qryNVunitsandGP'[Units]),0)

and this works perfectly at the table view level.

Division Franchise    Model                 Units           Profit   Profit Per Unit

A          Landrover     Range Rover        10             30000      3000

A          Jaguar           F - Type                 6             24000      4000 

B          Landrover     Discovery             12             30000      2500

B          Nissan          Pulsar                     6             24000      4000 

C          Nissan          Pulsar                     8             12000      1500

My problem arises when I try and create a line chart report and want to slice with filters for:

Division

Franchise

Model

and the result I am getting for these summaries is not correct.

It would appear that it is adding all the Per Unit figures together instead of having weighted averages.

I have only been using Power BI for a few days so please bear with me.

Hope you can help

Rollo