Question: Simple loop question

Consider the simple loop below:
> for q  from 1 by 1 to 12 do;
> if inter[q] <= B then xz[q] := inter[q] end if;
> end do;
inter[1] to inter[12] is defined previously
B is also calculated beforehand.
My problem is that Maple insists on looking for inter[13] and xz[13]. My range is between 1 and 12 so Maple shouldnt be doing this.
Can anyone please advise on what I can do?
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