Expect script(EQ3.exp) and error 65280

[CzarnyLewis]

Hello,

I have a problem with the script to control the radial valve. The script works in Putty (command line) on Raspberry, but the same script started from dzVents generates error number 65280. The error in the log looks like this:
"2019-10-11 23:45:35.751 Error: Error executing script command (/home/pi/eq3/eq3.exp). returned: 65280"

Where can I find error description for 65280? I've been looking for a solution for two days and nothing.