Check out the Knowledge base article titled: "Can I Fix a Corrupted Database in Lookout 4?" If you search the Knowledge Base with its document ID, 20RFHFJ6, you will get that article. This solution has always worked when I have had problems accessing the data in Citadel.
What will most likely work (as described in the article) is the deletion of tdx.tdx. I must caution you: Read the article before you proceed with any file deletions!
Regards,
Tommy Scharmann