help, beersmith2 spare volume is negative???

i'm new to this forum, i'm using beer smith2 and after adding my equipment, its giving me a negative volume for fly sparge. i'm not sure what i'm doing wrong, would love some advice.

Likely your equipment is set up wrong.  The sparge volume is calculated as follows:
  sparge_vol = boil_vol + grain_absorb - kettle_top_up + mash_tun_deadspace - mash_vol;

where boil volume is the target pre boil volume, grain absorption is the water absorbed by the grain, kettle top up is the top up water added post mash, mash tun deadspace is the deadspace (lost) volume from the mash tun and mash_vol is the total volume of water used in the mash.

All of these are listed on the "Vols" tab for the recipe so hopefully you can take a look there and see which one is out of wack.

Brad