Next birthdays block does not fetch the result correctly

Hi, I'm using drupal 6.20 with Birthdays version 6.x-1.0. I turned on a block to display a list of birthdays for the next 7 days. My problem is that the data that the block displays is not correct. For example, today is December 25, but in the list, birthdays within February 25 + 7 days are included.
You can have a look at the picture, it's what I describe.