Error checking routine - check range values on various worksheets and report if error

I think it might have something to do with this line:

If cell.Value <> 0 Or cell.Value <> 1 Then include_range_error_flag = 1  'wrong value in Include range so make error flag = 1

I changed it to look for cells that equal zero

If cell.Value = 0 Then include_range_error_flag = 1  'wrong value in Include range so make error flag = 1

This seems to work, i.e. if I change some of the ranges E3:E33 to zeros it reports those worksheet names, as it should. But the original line doesn't seem to work (look for values that are not a 1 OR 0)