A converted Roddy Grant try had given Edinburgh a 7-3 lead at the interval, only for Michael Swift's second-half try and a Dan Parks penalty to lift Connacht to victory.
Edinburgh had thought they had scored a second try when Jack Cuthbert went over, only for the score to be chalked off for crossing.
And De Luca admitted that his side simply did not have Lady Luck on their side after a month without a match.
"We came out here targeting a win but we were made to defend for large spells of the match and didn't get many chances to make our mark on the game," he said,
"We made the most of turnover ball with an opportunistic try early on and scored again in the second half only for it to be disallowed.
"There's a few new guys who were making their first start for the club so hopefully it'll be onwards and upwards and we can make our performances better from here."
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