you might want to check the historical movements for that day at flightstats.com

if you find that they delayed some and cancelled others you might have more ammunition.

yesterday i was told my flight to DUS was cancelled - there had been a lot of cancels and delays because of the fog, but the earlier flight was delayed for a few hours (until after my flight was scheduled to leave) and the later one ran (albeit late). the middle one (mine) was presumably cancelled for commercial reasons, as it clearly was not fog that stopped it going on time.