cDAQ-9181 with NI 9402 : After first read cycle Counter is missing some counts in all following cycles.

Hi,

I am trying to read TTL pulses from a function generator using a counter. I am applying a 1KHz signal to the counter. Every time counter reads the pulses correctly in first cycle of measurement, but it miss some counts in all following cycles.

I am using NI cDAQ 9181 Chassis and NI 9402 module with LabVIEW 2014 and NI Max 14.0.

My computer has Windows 8.1 operating system.

Please find the attached VI and image of Front Panel after RUN.

I also used the same VI with cDAQ-9171 USB chassis. Result were improved but the same problem still persists.

What could be the reason for that, please guide.

Thanks !

B. Sharma