Expression.Error: The column '' of the table wasn't found

[Anonymous]

I am linking Salesforce to Power BI and am attempting to concatenate rows if they have duplicate 'HP Opportunity Id' but it is telling me "Expression.Error: The column 'HP Opportunity Id' of the table wasn't found.
Details:
HP Opportunity Id" 

But my column is labeled 100% correct. Please let me know if you need more information

[MarcelBeug]

In step "GroupRows", you try to group the initial Source table, instead of the table from the previous step #"Sorted Rows".