Adding hours

This is an issue I had for a while but being just a personal project I haven't really pushed on working it.  However, based on the knowledge here, opposed to the general internet, I want to try this issue here.

I have a log with a starting and end timestamp, then a cell that figures the hours of elapsed time.  The time for each event usually falls around 23-26 hours.

TEXT(B16-A16,"[hh]:mm")

At the bottom of the log, I tried to compile totals for each data point.  The elapsed time column fails to total.  It gives zero.  I have tried just basic SUM, bringing it in a TEXT format.

 What am I doing wrong?

Thanks!