Importing time info from shapefiles is tricky, unfortunately, because there is no standard way to store time data. Position is well defined, but time is just an attribute that may or may not be named the same thing between shapefiles, and isn't guaranteed to hold the same format, either.
At least that's my understanding of it -- someone correct me if I'm wrong. So, basically, TF doesn't make a huge effort to look for and convert time stamps.
If there is a standard and you want to send us a file, we'd be happy to look into getting the values read in.
