I'm trying to create a report that is grouped by Serial Numbers (in this case) and then displays how many faults an item has had and its current location details, as shown in the example.

The report lists the correct data (as shown above) but I want to filter the data for items that have more than one fault and sort by the highest amount of faults first.
I've tried to filter the data using the expression Count(ColumnName) > 1 but this returns no data, so I assume I am doing something wrong. What would be the correct way of doing this?
Also am I using the right method for generating a report of this kind, I get the feeling I'm making things harder for myself than they really are?
Any help would be great!
Darren