Access can't append all the records in the append query

I am using tables individual by month. After converting my Select query to a Make Table query I managed to leave the Sales Dollars field blank (at this point it went unnoticed) . I continued, and created a Select query from the New Table (created from the Make Table query) that required the user to enter a parameter value (month) and then converted the query into an Append Query. At this point I ran into the
Error: "Access can't append all the records in the append query."
Research: I researched two sites one by Allen Browne and the other by Microsoft. Allen Browne's site was the most informative on understanding this error.

I recognized that the "null fields" or blank fields were the cause of the problem.
At this point I back-tracked and noticed that my Sales Dollars field was blank.
Hypothesis: Fixing the Sales Dollars field will allow all the fields to be appended.

I recreated the query that was originally made into a table. I ensured that Sum was selected in the Total section in Design View.
Solution: Fixing the Sales Dollars field allowed all the fields to be appended.

Wrap-up: make sure all your fields match with "Sums" and the appropriate "properties" and don't attempt to match blank sells with content cells.