IKJ52574I   UNABLE TO RENUMBER, "NEW LINENUM" new_linenum IS INVALID + FOR "OLD LINENUM" old_linenum, "NEW LINENUM" MUST EXCEED line_number_previous_to_old_linenum

The line previous to the old_linenum specification has a key greater than or equal to the new_linenum entry. This makes the assignment of new_linenum as the first renumbered line impossible.