I have two sample file in Power Query:
Two sample file

I would like to groupby and rank the sample data set. I was grouping the dataset based on Factor and YearNum before ranking it using = Table.AddRankColumn(#"previousStep","RankbyYear_WithInTheFactorLevel",{"YearNum",Order.Descending}) but seems it is not recognizing the previous step in power query. is there a way to get around this ? many thanks in advance.

I am trying to add a custom column in power query. if the column (A) has 6 digit number, I would like to contain the values from the B column, otherwise should contain values from the C column.