Problem With Import Listings Function

[gvAutoSaver]

When trying out the listing import function, I did the following:
1. Exported a listing that was already in the system. (Minus Listing ID to avoid confusion.)
2. Opened the exported spreadsheet, and changed the username (as well as removed the VIN).
3. Went to "Import Listings" in the admin section.
4. Selected the appropriate category, package, file type, etc. (I left "Activation Date" blank if that makes a difference).
5. Clicked "Import".

All appeared to work well, until I went to the user side and tried to look at the listing (both as a non-logged-in user and a logged-in owner-of-the-listing).  Although the listing showed up correctly on the "My Listings" page, when I clicked "View Details" I got the following:

Warning: array_combine() [function.array-combine]: Both parameters should have an equal number of elements in /[maindirectory]/system/lib/orm/types/TreeType.php on line 262

Warning: implode() [function.implode]: Invalid arguments passed in /[maindirectory]/system/lib/orm/types/TreeType.php on line 284

Catchable fatal error: Method TypeTreeDiplayer::__toString() must return a string value in /[maindirectory]/system/cache/smarty/user/gvauto/classifieds^%%7E^7E1^7E1E41B8%%listing_details_car.tpl.php on line 37

How do I correct this?  I have not made any changes to the ".../TreeType.php" file, but have made changes to ".../listing_details_car.tpl" (though not in the "/system/" directory, and changes were mainly to field names).  Non-imported listings show up fine.

[Arthur]

Hello.
Seems like problem in tree type field Make model. Please try to check this listings in admin area if they have both parameters.
If you will have any problems resolving this problem please contact support department with access information. Thank you.

Arthur