Add A new Thread cause a failure for the UR5e to response

Hi Everyone:
I came cross a technique question when I try to use a PC to send a customized URScript to UR5e using the Primary Interface(30001), like belowed:

First of all, I send a simple URScript to UR5e. It worked out correctly as I desired like belowed:

However, when I tried to add a thread to the above URScript and send it to UR5e like belowed:

It turned out that UR5e did not respond at all. I did not know the reason or technique question that may cause this failure. If someone have an idea about it, please let me know, thankfully for anyone’s help.