executable communicate with multiple devices through RS485 doesn't work

I have channelTest vi to test my devices, 4 of them through serie port using RS485 protocol and Modbus. Each of the devices are forced to different address numbers from 1 to 4. The Vi works fine. 

The weird thing is after ChannelTest is complied to exe, the serial devices are not responding, but the "stop" button in the program still functioning. I am using same computer to test both VI and exe. 

I make another program to test one of the devices, both VI and exe works.

It looks like the exe doesn't work properly with multiple devices. Another thing is ChannelTest.exe works in one of my friend's computer. I have installed VISA run time engine in my computer, it still didn't solve the problem.

sounds like i need to instal something in Labview run time engine, but I don't know what. Any one has similar experience?

Thanks!