Debug/Catch Trigger error

Debug/Catch Trigger error

I have a trigger on one of table for insert. I use C#'s BulkCopy feature
to insert millions of record in Temporary table without trigger and than I
transfer those record to main table using Insert into .. () select () frm
temptable syntax.
Main table has trigger, however I didn't get a good success on this, since
I get trigger to main table. it seems as one of record is causing an error
that force rollback of complete insert statement. How I find that culprit
row? Or maybe I am wrong then why it is failing most of time, but does
work with limit data set of row.
Is there anyway I can track or catch exception in Trigger working?