Need help with diffing times (commented code :) )

[ericonline]

Hello, (didn't want this to get buried because the other thread was marked with a Solution")

I really need help determining the difference between two times. This is quite a challenging undertaking! 

Two Date+Time cards: 

Code (get your wading boots on!): 

//Concatenate the diffed Hours, ":" and diffed Minutes//

Concatenate(  

//Convert the diffed Hours and Minutes to Text//
  
    Text(    

//Perform DateDiff to determine difference between Hours//

        DateDiff(

//Use DateTimeValue to format the text string to Hours//

            DateTimeValue(

//Get start date, hour and minutes into a format that DateTimeValue likes. Note the Char(13)! (clever)//
                    
                    Concatenate(
                        Text(
                            startDate.SelectedDate,DateTimeFormat.ShortDate),
                        Char(13),
                        Text(
                            Concatenate(
                                startHour.Selected.Value,
                                ":",
                                startMinute.Selected.Value),ShortTime)),"en-US"),
            DateTimeValue(

//Get end date, hours and minutes into a format that DateTimeValue likes. 

                    Concatenate(
                        Text(
                            endDate.SelectedDate,DateTimeFormat.ShortDate),
                        Char(13),
                        Text(
                            Concatenate(
                                endHour.Selected.Value,
                                ":",
                                endMinute.Selected.Value),ShortTime)),"en-US"),
        Hours),"[$-en-US]##"),
        
        ":",

//Do the same thing for Minutes//

    Text(
        DateDiff(
            DateTimeValue(
                    Concatenate(
                        Text(
                            startDate.SelectedDate,DateTimeFormat.ShortDate),
                        Char(13),
                        Text(
                            Concatenate(
                                startHour.Selected.Value,
                                ":",
                                startMinute.Selected.Value),ShortTime)),"en-US"),
            DateTimeValue(
                    Concatenate(
                        Text(
                            endDate.SelectedDate,DateTimeFormat.ShortDate),
                        Char(13),
                        Text(
                            Concatenate(
                                endHour.Selected.Value,
                                ":",
                                endMinute.Selected.Value),ShortTime)),"en-US"),
        Minutes),"[$-en-US]##")
)

But this results in: 

How do I get the correct times to display? 

Thanks

[ahohman]

I'm hoping you can give me some suggestions for this.  I've been struggling all day.  I used your most recent sample (which is great to have), and I applied to my test, and I can't get it to work.  I've added a screenshot of my test and the code I'm using below.  The only difference is that my fields reside in datacards.  Is that the problem?  I need to save the times submitted (as well as the calculation) back to SharePoint.  Any advice you can provide is appreciated.