Format the average of a duration

Here's a variant of the DAX from Greg_Deckler et al as discussed in http://community.powerbi.com/t5/Community-Blog/Aggregating-Duration-Time/bc-p/91032#M328   It uses Duration rather than number of seconds to calculate an Average.

Duration Average = 
// Duration formatting 
// * @konstatinos 1/25/2016
// * Steve Wheeler 22/11/2016 - converts from days (default format for Power Query's) Duration data type, rather than seconds
// * Given a number of days, returns a format of "d.hh:mm:ss"
//
// We start with a duration in number of seconds
VAR Duration = AVERAGE(Calls[Call Duration])

// The days will be the whole part of the Duration
VAR Days =
    INT (Duration)
// There are 24 hours in a day
VAR Hours =
    INT ( (Duration - Days) * 24)
// There are 60 minutes in an hour
VAR Minutes =
    INT  ( (Duration - Days - (Hours / 24) ) * 24 * 60)
// Remaining seconds are the remainder of the seconds divided by 60 after subtracting out the hours 
VAR Seconds =
    ROUNDUP((Duration - Days - (Hours / 24) - (Minutes / (24 * 60)  ) ) * 24 * 60 * 60, 0)
// These intermediate variables ensure that we have leading zero's concatenated onto single digits
// Hours with leading zeros
VAR H =
    IF ( LEN ( Hours ) = 1, 
        CONCATENATE ( "0", Hours ),
        CONCATENATE ( "", Hours )
      )
// Minutes with leading zeros
VAR M =
    IF (
        LEN ( Minutes ) = 1,
        CONCATENATE ( "0", Minutes ),
        CONCATENATE ( "", Minutes )
    )
// Seconds with leading zeros
VAR S =
    IF (
        LEN ( Seconds ) = 1,
        CONCATENATE ( "0", Seconds ),
        CONCATENATE ( "", Seconds )
    )
// Now return hours, minutes and seconds with leading zeros in the proper format "hh:mm:ss"
RETURN
    CONCATENATE (
        Days, CONCATENATE (".", CONCATENATE (H, CONCATENATE ( ":", CONCATENATE ( M, CONCATENATE ( ":", S ) ) ) ) )
    )

Change the column on which you calculate in the VAR towards the top and it should work in your table but, as text rather than numeric, can't be used as a chart axis or in other measures etc.  

Bring on that Duration data type...:)