Ok, I have tested it.
At first, I got the same error as previously.
But, given the fact that this version (4.20) from Nation, is so close to the actual one, I thought that maybe the "devil" is somewhere else.
I tried to change the settings on kfloppy emulator and disabled both options: "Large transmit buffers R-J robots only" and "Verbose messages".
The loading procedure continued normally, the file was loaded without errors and finally the script run with success!
I will test the binary files from the newer versions as well, to check if the problem was the settings from kfloppy after all.
I do not have words to express my gratitude to all of you participated!
I am not used to searching and writing in forums, and so the fact that you helped me to find a solution,
was a great experience and made me eager for the future to have the chance to give back!!
Regards!!