I have a table that in one column lists a date and in another column a dollar
amount.

On the same sheet I have second table that in one column lists a date. In
another column I want to add up the dollar amounts from the first table for
dates equal to or less than the date in the second table.

I thought that SUMIF would work, but it is not. I am getting zeros. I
think there is a problem with the criteria. I used <=D12, where D12 is the
cell in table 2 that contains the date. (I also tried it with quotation
marks). But it is not working. Any suggestions?