Function returns different results in different rows
 

This one has me stumped. I created the following COUNTIFS function to crunch some data:

=COUNTIFS(Sheet1!$A:$A,"=x",Sheet1!B:B,"<"&Sheet1! $C:$C)

As you can see, this formula performs two checks:
Column A = x; and column B < column C;

Data in column A is either "" "x" or "m".
Data in Columns B & C are numbers between 0.00-10.00. (with 2 decimal points)
Sheet1 has a text header row. (I have recreated the sheet without this row and got the same results)

When I drag this formula down to the row below it, it returns different results for each row. When you look at the formulas in each cell, they are exactly the same; they just return different results. I tried rebuilding the data and formula in a new workbook and the exact same thing happened.

I shared a workbook that demonstrates the problem he

https://docs.google.com/leaf?id=0B4L... FhZTQ3&hl=en


Any clues anyone?