Sum based on horizontal and vertical match

Okay. I am trying to get a sum based using the top row headers and the answer in column A. Originally this was an easy index match sort of thing, but then my report grew and now I need the sum of these.

I am attaching a very simple randomly inputted spreadsheet to give the example. So, using the example. The "Data sheet" has animals listed in Column A and date headers in B1:C1. On the results sheet in B2 I need the sum of every time the result of A2 and B1 meet on the Data sheet. I have NO idea how to do this.

Please keep in mind, while this seems extremely simple on this sheet, my actual worksheet is pretty huge and constantly changing, so I don't want to have to assign columns for a normal sumif.

Thanks in advance for your help.

Test Worksheet.xlsx

The only problem with that is the headers don't match as easily as I made it seem. And they aren't consistent. So, while I currently need 5/1/13 the data sheet may actually start with 6/1/11. So, it's not an easy column match.

I love when it's so much simpler than I make it! Thank you SOOO much!!!