count hours from 2 dates

hello, um using this SQL string :

     SELECT computer, date, closedate,UNIX_TIMESTAMP(closedate),
     UNIX_TIMESTAMP(date), (UNIX_TIMESTAMP(closedate) -
     UNIX_TIMESTAMP(date)) / POW(60,2) FROM tracking (18 Records)

computer date closedate UNIX_TIMESTAMP(closedate) UNIX_TIMESTAMP(date) (UNIX_TIMESTAMP(closedate) - UNIX_TIMESTAMP(date)) / POW(60,2) 45 2002-06-19 14:12:22 2002-06-19 16:21:10 1024500070 1024492342 2.14666667 13 2002-01-28 10:04:56 2002-02-19 15:00:30 1014130830 1012212296 532.92611111 96 2002-06-19 15:46:00 2002-08-21 15:18:21 1029939501 1024497960 1511.53916667 45 2002-06-25 15:42:45 2002-06-26 11:11:27 1025086287 1025016165 19.47833333 239 2002-06-26 15:07:25 2002-06-27 17:21:38 1025194898 1025100445 26.23694444 188 2002-06-27 10:52:35 2002-06-27 17:55:48 1025196948 1025171555 7.05361111 173 2002-07-02 15:06:27 2002-07-02 15:29:01 1025620141 1025618787 0.37611111 43 2002-07-03 17:50:22 2002-08-21 15:17:28 1029939448 1025715022 1173.45166667 45 2002-07-09 10:54:56 2002-07-09 12:32:07 1026214327 1026208496 1.61972222 37 2002-07-09 10:57:50 2002-08-01 16:53:30 1028217210 1026208670 557.92777778 12 2002-07-17 10:24:37 2002-07-18 16:28:19 1027006099 1026897877 30.06166667 9999 2002-08-21 15:28:11 2002-08-22 14:46:48 1030024008 1029940091 23.31027778 25 2002-08-30 11:01:53 2002-09-04 10:55:27 1031133327 1030701713 119.89277778 151 2002-09-04 10:01:25 2002-09-04 10:38:42 1031132322 1031130085 0.62138889 43 2002-09-06 19:00:47 2002-09-09 15:25:30 1031581530 1031335247 68.41194444 182 2002-09-19 15:57:44 2002-09-23 10:22:53 1032772973 1032447464 90.41916667 193 2002-09-20 10:53:00 2002-09-27 17:48:46 1033145326 1032515580 174.92944444 6 2002-09-23 10:24:27 2002-09-23 11:10:35 1032775835 1032773067 0.76888889 im converting seconds to hours with POW ... 1 hour = 60* 60 seconds i maked and example in RED ... why do i get that mouch hours diference in cases where the dates are days apart ????