Chapter Numbering Help

I'm trying to number the second level heading ("Mounting Instruction") in the form 2.1.  I believe I'm using the correct Number formula in the "Number" field, but it won't change from 2.2.  I set the 1st level heading "Technical Information" to start at 2 as I assume it's best to start a new chapter with each section.  Any thoughts?  Thanks!

1st level heading ("Technical Information") settings:

2nd level heading ("Mounting Instruction") settings: