QBASIC and ARRAYS

in my qbasic program, i keep getting subscript out of range, but am sure i made enough, my program works for the first 2 arrays, but once i add the if then after the ==== it tells me subscript out of range.
this is what is going on >>>

DIM prices(1 TO 7), lestype$(1 TO 7)
FOR n = 1 TO 7
READ prices(n), lestype$(n)
NEXT n
DIM location.total.owed(1 TO 6)
DIM location.names$(1 TO 6)
DIM location.customers(1 TO 6)
DIM location.lessons(1 TO 6)
DIM city$(1 TO 6)
FOR n = 1 TO 6
location.total.owed(n) = 0
location.customers(n) = 0
location.lessons(n) = 0
NEXT n
city$(1) = "Dearborn"
city$(2) = "Canton"
city$(3) = "Novi"
city$(4) = "Southfield"
city$(5) = "Detroit"
city$(6) = "Other"

location.names$(1) = "DEA"
location.names$(2) = "CAN"
location.names$(3) = "NOV"
location.names$(4) = "SOU"
location.names$(5) = "DET"
=================================
locat$ = UCASE$(locat$)

IF locat$ = location.names$(n) THEN
location.total.owed(n) = location.total.owed(n) + 1
location.customers(n) = location.customers(n) + 1
location.lessons(n) = location.lessons(n) + 1
ELSE
location.total.owed(6) = location.total.owed(6) + 1
location.customers(6) = location.customers(6) + 1
location.lessons(6) = location.lessons(6) + 1
END IF

PRINT USING N6$; city$(n); location.customers(n); location.lessons(n); location.total.owed(n)

What's the locat$ variable define in your code??

u read locat$ from the data

the locat$ variable is a parameter which u input??

its in the DATA line after the program, its a program for school, so the data is typed after the program. i dono what parameter means

it is valid its working like it is supposed to, the problem is in the arrays

Do u have a mistake in your code,because i couldn't find UCASE$ in QB!

UCASE$ like LCASE$ is one of those codes already in the program, it makes something all caps or all lower case.
the problem was in my FOR NEXT i dont understand those, the teacher showed me what i did wrong, but i didn't understand. so if u know a easy to follow tutorial for those with short attention span on FOR NEXT and ARRAYS ill be thankful.

U can find some tutorial on network for learn QB syntax:http://www.tutorgig.com/showurls.jsp?group=798&index=1

thanks man