Numbers doesn't reflect reality

I brewed a batch yesterday (My first where I was able to extract som good numbers to fill in kettle and mash profiles). After filling in all the data, and I return to the reciepe and go to mashing volumes it tells me to fly sparge with 4 litres less than what was used before, to get the batch size we got.

I've been fiddeling around with numbers and both my kettle and mash numbers are pretty accurate. But I can't understand why BS tells me to fly sparge with 4 litres less than we did, and claiming I will end up with the same batch as yesterday. As far as I know I would end up with 4 litres less wort.

Please help, is there something I'm missing? I'm pretty new to this, as you probably can tell.

Hi,
  In most cases this type of problem is an issue with your equipment profile.  BeerSmith basically calculated back from your target batch volume to estimate the pre-boil volume (including losses and boil off) and then works back again from there to calculate your sparge vol needed (subtracting losses and water absorbed in the mash).  If you look at the "vols" tab you can often see what the volumes are and how they are calculated by walking backwards.

  If you measure your volumes at each step and compare them to the vols tab and your equipment profile you can probably zero in pretty quickly on which setting is off.

Brad