Fluent Nhiberhate And Missing Milliseconds

Question

I am using Fluent Nhibernate and Nhibernate for my current project. I need to record the time to the millisecond. I have this for my mapping

            Map(x => x.SystemDateTime)
            .CustomType("Timestamp")
            .Not.Nullable();

I genertaed the hbm.xml files and the line is the following:

<property name="SystemDateTime" type="Timestamp">
  <column name="SystemDateTime" not-null="true" />
</property>

I have read this is the fix, but the records in the database do not have the milliseconds. Has anyone solved this issue. And I have tried CustomSqlType also.

Thanks