Turbo Compiler issue

[dilwyn]

Most likely this has nothing to do with it, I see an imbalance of IF/THEN/ELSE/END IFs in there, although it's a shortened listing so the extra END IF may be there, just not shown.
As tofro said, the likeliest thing is a close mismatch of names used as parameters and as other variables elsewhere.
Also sometimes when these sorts of structure-dependent things happened, sometimes it pays to restart the system and reload the program, in case of something happening to the nametable. Had this sort of thing happen to me before - I sometimes fail to resolve it satisfactorily and end up just writing it a little differently to work around the problem.

[tofro]

No, I don't have.
I will give MasterBasic a try when I'll find time for it. I have not used it because I write the code on PC, in Notepad++ and save it on a DOS drive that is mapped both in QPC and QEmulator, so I can test the program simultaneously in Minerva and SMSQ/E.

That still works well (i.e. you can still save to a dos_ drive). MasterBasic isn't helping much to enter or edit a program (it just uses the standard S*BASIC editor), but rather helps you understand your code, find and navigate to places once you struggle to do so. In fact, it brought me back from your way of working to the S*BASIC editor. (and I really got bored of typing line numbers...)