Try forcing the underlying table type in your entity map:
<property name="DatePosted"
type="timestamp"/>
See
1.2.2 The Mapping File. If you scroll down to the third paragraph after the fourth code block, you'll see this:
Quote:
In some cases this automatic detection (using Reflection on the Java class) might not have the default you expect or need. This is the case with the date property. Hibernate can't know if the property (which is of java.util.Date) should map to a SQL date, timestamp, or time column. We preserve full date and time information by mapping the property with a timestamp converter.
In your class you're using DateTime (and a totally different language and platform :), but I suspect it's the same issue.