When you work a drop stitch fabric in a pattern you usually only drop down a small number of rows.
As you work  you increase (by adding a yarnover) into your work. It can be seen in this photo several rows below the working row.
This yarnover will later become the stitch you drop down, it will only drop as far as the row you created the yarnover.

Just check that you are dropping the correct stitch and it should work perfectly for you!