> so if anyone can give me some clues about the causes of that returning value -1 Your array indexes for `values[...]` are wrong, so the final one is passing invalid memory to bind. Array index start at 0, not 1. Bind indexes, on the other hand, start at 1. Whether that is *the* problem, i don't know, but it's certainly *a* problem. (Apologies for the brevity, but am working from a tablet.)