Diggit Drupalextras

Ok, so here's my problem, I'm attempting to update from 6.17 to 6.19. I go through all the steps, and after I'm finished running update.php, I get back to my site and it says I'm still at 6.17. I can't think of anything I may be doing wrong... I make all my backups, place my site in offline mode, put it in the default theme, disable my modules, then I replace all the files and put back the contributed modules and themes. I run update.php and get everything back to working order and... Nothing has changed. Drupal still identifies itself as 6.17 and says I need to update. What could I be doing wrong? Any ideas?