I have the following code loop:

for i=0, rows-1 do begin
READF, lun, a, b, c, format='(A15,1x,F0,1x,F0)'
filenames[i] = a
latitude[i] = b
longitude[i] = c
help, a,b,c,i
print,a, 'a'
endfor

and get these errors:
% Variable is undefined: FILENAMES.
% Execution halted at: $MAIN$ 1
/home/phaines/climate/idlist_files/write_idlist_1.pro_test
% Variable is undefined: LATITUDE.
% Execution halted at: $MAIN$ 1
/home/phaines/climate/idlist_files/write_idlist_1.pro_test
% Variable is undefined: LONGITUDE.

What do I do to fix this?

Thank you.