How to calculate the difference between 2 durations?

[Anonymous]

Hello everyone,

I am calculating the duration between two periods but I have no result

Here is my problem :

Number of the action  Duration of the start action  Duration of the end action    Duration inter-Action (?)             

1                                    04:13:54                                              05:07:30                           

2                                    05:25:54                                              03:26:30                       (05:07:30) +(05:25:54)

3                                    03:23:05                                              02:45:58                         (03:26:30) +(03:23:05)

4                                    05:14:36                                              03:09:30                         (02:45:58)+ (05:14:36)

5                                     04:39:56                                              03:56:30                          (03:09:30) + (04:39:56)

I would like to calculate this field : '' Duration inter-Action''. The calculation consists of adding the Duration of the end of the action of the previous action with the  Duration of the start of the action of the number of the current action.

Thanks for you help,

Heisenberg