Hi Majid,
why do you insist on using FormatIntoString when there are other conversion functions available?
See this:

Why do you wire the FPGA reference across the loop?
How/why do you close the FPGA reference when the loop never stops?
Why is there no error handling?
Best regards,
GerdW

using LV2016/2019/2021 on Win10/11+cRIO, TestStand2016/2019