急！求助rename报错了

Renaming components on BOTH_SIDES on entire BOARD
Extents: (-18355.07,-18355.07) (43654.90,43654.90)
Sequencing the Reference Designators SEQUENTIALLY
Row processing direction : to the RIGHT, from the top down.
ERROR: No grid lines found on top side, aborting.
问题如上，请问怎么回事呢？