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Is "starting" a counter the same as "arming" it?

Hi everyone,
I am trying to understand why I get unexpected behavior with my VI and counter output.
I am outputting 3 single,triggered pulses: 2 on a 6602 (1 each on counters 0 and 1), and 1 on GPCTR0 on a 6071E.
The second pulse on the 6602 (on counter 1) is supposed to immediately pulse after the first pulse (on counter 0) is finished pulsing.
GPCTR0 is a pulse used to start my data acquisition, and occurs before the first pulse from the 6602.
All three counters share a common hardware trigger, a repeating 120Hz pulse, synced to some of my other hardware. This train of triggers arrive only after I switch a DIO line (on yet another card, a 6503), and this DIO line is turned on the a sequence frame after the frame in which I set up and "start" my counters (with control.vi set to "start").

Now here's the problem I encounter:
*most* of the time (~4/5 times) I get the output I want from the 6602, 1 pulse right after the other. But every once in a while, I get the pulses ~8 ms apart--that is, counters 0 and 1 are triggering off different trigger pulses in the 120Hz I send to the gates. So one of my counters is somehow missing seeing the start trigger that another counter sees.
How can this be? If all counters are already started, shouldn't the same start-trigger trigger all of the counting operations at once?!

Also problematic, every once in a while, counter 0 is missing the first hardware trigger, but triggers on the second trigger of the 120 Hz trigger pulses. So it seems my problem is that the counters are sometimes just missing seeing the triggers.

Any ideas? I posted my VI. The relevant portions are in big frame3, inner frames 3 and 5. (frame 3 configures and starts all counters. frame 5 turns on my hardware triggers).
thanks in advance for any help!
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to answer my own question....
i discovered something miswired in my hardware.
so there seems to be no labview problem...
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