What was the reason for the clash with the interplanetary officials?

The boy's parents clashed with Inter-planetary officials because they were unable to get their son's gift through customs. His gift exceeded the allowed weight limit.

So when, at the customs table, they were forced to leave behind his gift, which exceeded the weight limit by no more than a few ounces, and the little tree with the lovely white candles, they felt themselves deprived of the season and their love.