[themes] core compatibility

We're seeing a weird problem in our Drupal themes administration. We've used Deco as a starting point for a customized theme. We then copied this theme to a new directory (in sites/all/themes) called ourtheme. We modified the deco.info file to list "ourtheme" as the theme name and saved it as ourtheme.info. We also made a new screenshot.png. The trouble is, in the themes list in administration the list shows "This version is incompatible with the 6.2 version of Drupal core." and lists no theme name. We can select it as the default theme but it still shows no theme name in the configure theme page/ Ideas?