[ic] How to debug: Error during creation of order routing log

[interchange-users@icdevgroup.org (ffire)]

How can I debug this "Error during creation of order routing log" 
problem?

Received this error from error.log, generated at the Checkout page 
when I click on "Place Order":

Error during creation of order routing log:
Route log failed. at /usr/local/interchange/lib/Vend/Order.pm line 
1575.

I've also checked through the other 3 files under /logs (usertrack, 
tracking, log), but nothing is telling me what's wrong with my 
log_transaction file.  Previously the whole Checkout procedures 
worked, then I made the big mistake of modifying the log_transaction 
file, as well as the database (ie, add more varchar, add fields, 
etc), that when I retest again, it's not working  :(  There's no way 
I can remember all the changes I've made  :P  Are there other logs I 
can look at, etc?  How can I go about debugging?