The assembler put together the two bookcases well but I mistakenly did not bring in the back panel of each one.  I pointed this out when he was done but, since the back panels were not present, he left.  I later discovered them among the packing materials which I left by my front door.  The assembler should have noticed that something was wrong because the assembly instructions clearly indicate the installation of the back panel and there were a large number of nails left over after he completed the other steps.  I’ve nailed in the back panels myself.