CR 10 Pro, SQL 2008 R2 - NOVICE CR user

The report works great, comparing date/time of when a ticket is created and when work has started o the ticket by using the first time log entry and get an average of each ticket individually but need an average of all the tickets during a specified period of time.

Fields/Views used:
tblServiceOrders.TimeReceived (formula combines date and time received)

Trying to get an summary average from a DateDiff formula, which is placed in GF3 :
DateDiff('n',{@DateTimeRecvd},{tvwr_TimeTransactio ns.StartDateTime}

Also used format editor to change the display string to using this formula:
totext(truncate((DateDiff('n',{@DateTimeRecvd},{tv wr_TimeTransactions.StartDateTime}))/1440),0,'') + ' days ' + totext((remainder((DateDiff('n',{@DateTimeRecvd},{ tvwr_TimeTransactions.StartDateTime})),1440)/60),2,'') + ' hours'

I used the Insert Summary, chose the DateDiff formula and configured to calculate Average summary and place in RF and it spits out a set of numbers like: -38,097.25 instead of what I'd expect, someting like 2 days 18.10 hours.

Any ideas on how I can get the summary average to work?