SELECT SUM(lss1.hours + lss2.hours) AS totalhours FROM lss1, lss2
so we SEE a problem here? You're summing both tables. That query really doesn't even make sense... SUM as the only return parameter should only return by matches... I think you want two separate queries to get the totals from EACH table, not a total from BOTH tables... or are you trying to add them together and sort by the result? If so that would require a UNION or JOIN operation.
Though I should probably read you the riot act; this is 2014 not 2004, stop using the deprecated mysql_ functions we've been told for the eight years since PHP 5 dropped to stop using, and that for over two years now there have been giant red warning boxes in the manual telling us to "CUT IT OUT!!!"
Which is also why you shouldn't be blindly dumping variables into your querystrings.