Multiple Conditions in Custom Column

Hello, I was hoping someone could point out what I am doing wrong. 

I am using Power Query to check two columns for conditions and if they relsove to be true then update a third column. What I have so far is below

= Table.AddColumn(#"Replaced Value34", "Custom", each if [HDX_Domain] = "CPR" and [label] ="None" then "$CPR"
else if [HDX_Domain] = "CPR" and [label] is null then "$$$CPR"
else [label])

The first part works when it finds "None" in the [label] column, however I cannot seem to get Power Query to recognize the null in my column.

Thanks