Reporting Services :: Convert Milliseconds To HH:MM:SS

I am writing a report that Queries a SQL DB using 'SQL Server Business Intelligence Development Studio'. I have a field in the DB called duration and it is in milliseconds. I am trying to find an easy way to convert the format from Milliseconds to HH:MM:SS.Nearest I can get is the following for the field:

=Int( ((Fields! DURATION.Value/1000) / 60) / 60) & ":" & Int(((((Fields!DURATION.Value/1000) / 60) / 60) - Int(((Fields!DURATION.Value/1000) / 60) / 60)) * 60)

The output is in HH:MM. One issue with this is if the MM is say :03, it prints as :3. I lose the leading 0 so 9:03 (9hrs and 3 minutes) prints as 9:3. Where as 9:30 (9 hrs and 30 minutes) prints as 9:30 as it should.