Multi SRF04 with 7 Segs LED indicated

Hi everybody,

I'm a new member of Arduino
I'm trying to doing small project with SRF04 + 2x7 Segs LED display and Arduino Mega 2560
Totally, i have 15 SRF04 to install at 15 location to measure the distance of each location, if the each distance reach my setting (min is 10cm and max is 100cm) the 7 seg LED with be shown the location (indicated the number of location).
2x7 segs LED is driving by 2x74595 for each 7 seg.
the button for reset and indicate is 00.
one by one of SRF04 is ok, but multi SRF04 connected cannot
Could you please advise me the idea