Custom Column error - seeking nested IF results from date range |Power Query|Excel Forum|My Online Training Hub

Hi All, 

first time post. Self taught newbie on PQ. I have spent the day searching other threads for the answer to no avail, so here I am. Trying to follow the rules!

Experiencing - Expression.Error: We cannot apply operator < to types Number and Date. I get that this is probably a formating issue but I can't work out the fix.

Please see sanitised dummy workbook replicating problem. 

Data is appended sales data from 2 systems(formats) to cover a continuous sales period. New base data added weekly to folder before refresh in PQ. The transform part works perfectly!

The main game is producing a sales dashboard via pivots showing target revenue based on last FY (by month).  Enter my custom column for targets. Previously it worked but was a simple [Sale]*1.1 but now the sales team rightly want some adjustment to reflect reduced capacity during COVID lockdowns. I am using the formula below and getting the error shown:

Really hoping you can have a laugh at a simple problem and help me out!

Very happy to be told I need to reformat the data and use a different formula as I've considered that type of solution but felt date ranges should be something commonly done?

Regards

Ian