How to sum datediff in SSRS

I hv two fields

StarTime

EndTime

both are DateTime.

And I need to get the sum of StarTime and EndTime

if i hv data as below:

Name StartTime EndTime

A 3/10/2014 01:00:00 PM 3/10/2014 08:00:00 PM

A 4/10/2014 01:00:00 PM 4/10/2014 08:00:00 PM

so i will get

Name TotalWorkingHour

A 14:00

what should i write?

I write this line on ssrs

=Datediff(“h”,Fields!TglJamBerangkat.Value,Fields!TglJamPulang.Value) & “:” & Datediff(“n”,Fields!TglJamBerangkat.Value,Fields!TglJamPulang.Value) mod 60)

but when i add

=sum(Datediff(“h”,Fields!TglJamBerangkat.Value,Fields!TglJamPulang.Value) & “:” & Datediff(“n”,Fields!TglJamBerangkat.Value,Fields!TglJamPulang.Value) mod 60))

it returns #error