How do I add a column of time values

I keep a spreadsheet of my workouts. I track lots of information, one of which is duration

In Excel and Google Docs, no problem. When I convert my Excel spreadsheet to Numbers the column displays an error that says "The formulas Arguments can only include one Date Value"

Example: Rows 2-32 contain various time values such as:

00:25:32 (0h25m32s)

01:36:59 (1h36m59s)

That should add up to 02:02:21 ... Excel and Google Docs it's just a simple =Sum(<first row>:<last row>)

(the 00:00:00 is the only thing entered in the columns, the ( ) in the examples is just for clarification of the data)

Numbers doesn't like that however and just displays the error above ...

What simple thing am I missing? Or is it not so simple and I'm just not seeing what I need ...

Thanks!