The DeBsp is not for Quake II. It's for RtCW (Return to Castle Wolfenstein).
how to decompile most sin,doom2,quake,quake1,cs,halflife,rtcw quake3,sof1, kingpin and paintball any maney other bsp maps
first make folder on desktop or anywhere unzip debsp to that folder
now put a bsp file in that folder
now open debsp now we need to find a bsp file click browse
point to bsp in the folder once this is done click on decompile
that its now you have a map file now all have do open map editor open the map file
note: be sure before you decompile a bsp into a map file always ask the owner and get his permission. to use and editor another persons work.