deleteRow or updateRow after insertRow

does anyone know why this happen?

I do first:
ResultSet.moveToInsertRow();
ResultSet.update...(1, ...);
....
rs.insertRow(); // a new row inserted into table

but after that, I may move to some other row, say using Result.absolute(..)
or so, and then
1. update
ResultSet.update...(1, ...);
...
ResultSet.updateRow(); // it does not update the corresponding row in the
table, but also no
exception thrown.

2. delete
ResultSet.deleteRow(); // throws exception: Can not call deleteRow() when on
insert row.

anybody has any clue? thanks

zhenchang