If you have two fields in the row area, the first field is the outer
field. Since you only have CellName in the row area, you can't insert a
blank line.
However, you could move ID to the row area, below CellName
(that will make CellName an outer field)
Then, double-click on the CellName button
For Subtotals, select 'None'
Click the Layout button
Check the 'Insert blank line after each item' box
Click OK, click OK