Be sure each column used has one bubble filled in.
Be sure each column used has only one bubble filled in.
Check to see that you have not placed a bubble in the wrong column.

The illustration below is an example of the placing section of a score sheet.
In this example four classes were judged.
The placings for these classes were as follows.

Class 1:   2-1-3-4
Class 2:   3-2-1-4
Class 3:   4-3-2-1
Class 4:   1-2-4-3