Manivannan,
There probably aren't any rows yet in whatever table that is. That is why it is safe to set it to the first row after the append. Normally it goes like this:
tbl.appendRow();
tbl.setRow(tbl.getNumRows()-1);
You could change it if desired, but my guess is that there will only be the one row in the table in whatever routine is running there during the edit.
Jason Latko - Senior Product Developer at SAP