There is a new property called fuelCrossFeed. Setting this to True will allow fuel to pass through it. Setting it to False will prevent it. You aren\'t by chance trying to load a craft from an older version? Also, next time you get that error, open the Debug window(ALT-F2) and look to make sure it\'s this part throwing the error. It should still work but it does need a tweak to the config file. stageAfter = True stageBefore = True Should be changed to stageOffset = 1 childStageOffset = 1 Also, if you want to activate fuel crossfeeding, add the following line to the config (where doesn\'t matter, I put it after the MaxTemp value) fuelCrossFeed = True Arrr! Capt\'n Skunky