Excel tries its best to figure out what we want when we don't tell it
enough. To ensure that Excel uses the columns you want for categories
and the rows you want for series names, make sure the cell(s) at the
intersection of these rows and columns are blank (completely clear, not
just "" as a formula might return). So your example data would look like:

Ans Missed AqT Man
08:00-08:15 148 56 43.275 80
08:15-08:30 153 18 11.9996 90