Speedlite 580EXII constantly turning off during shoot?

[BJWOK]

hi folks,

i have a problem. when shooting with my d-lites triggered via the cable and two additional speedlite 580EXII's firing via whatever the signal sent from the d-lites is (forgive my ignorance of how it actually works) i noticed one of the speedlites would switch off after a few minutes - the red light would disappear and the flash would not fire. i changed batteries and the same result. i had the two speedlites on M to avoid any preflash triggering and hence sync issues, but had to constantly turn that one speedlite on and off to get a result from it.

here's the setup. any thoughts?

interestingly it looks like they are both not firing in this shot??

[Curtis N]

The instruction manual is your friend.

Custom function 01 is for the auto power off feature. Set it to 1 and it will stay on until the battery dies.

[BJWOK]

curtis thanks for that mate! indeed, one of the speedlites had custom function 01 set to 1 already (a mate had borrowed it) and the other (suspect one) indeed had it set to 0. cheers for the help!