I have a report where the data is grouped by IP Address (one of the fields in the db). I wanted to display only the Top N groups, however the group sort expert was grayed out. So, I created a summary field to enable the group sort. However, it will only let me sort the data based on that summary field and nothing else.

Is there any way I can sort the data based on another 'non-summary' field?

Let me be a little more clear, I have one summary which counts the total number of failed transactions for each group and another summary which gives me an overall number of transactions for each group.  I also have a formula field called 'failure rate' which is basically equal to CountofFailed/TotalCount.

However, I cant get Crystal reports to allow me to sort by the failure rate.