b and g must be aligned

Hi all, We're hitting this error "b and g must be aligned". I tracked the src to a commit about some alignment code thing in gdk_calc: http://www.mail-archive.com/checkin-list@monetdb.org/msg09731.html (Fix alignment conversion in compatibility code for grouped aggregates.) Can you guys please explain what's the reason behind this error? I can't understand by just looking to the src of gdk_calc.c Thanks!