Total duration time displays incorrectly

Hi,

When I publish or when I look at the Slide Properties, it shows my presentation as 6 minutes for the total time but it is actually supposed to be 41 minutes.  The checkbox under Player Templates >> Player Controls >> Elapsed and Total presentation time is checked. I have previously, on a different computer, been able to get the total time showing as 41 minutes.  Do you know if there is something that maybe I haven't checked off so the total time shows correctly?

Thanks