I removed the gray commented code,
and added, the code in the green rectangle . . .
but what I can't understand is because the same code,
yesterday morning, like many many other times,
worked perfectly,
and since yesterday afternoon it returned an error. . .
. . . rereading the code, with the modification suggested
by Lee Mac and Marc'Antonio Alessi
it seems absolutely right to me. . .
but I don't understand why it worked before. . .
anyway thank you all for your kindness and help.
Have a nice day to all
ciao