Dear Bhanu,
The concept is you cannot append the internal table which is declared as sorted you should always Insert the internal table
So when you write select with appending it gives dump.
A table index administrates the logical order of table rows. As the primary table index of a standard table for managing the order arising from index operations. However, the order in the index has no relation to the content of the table rows But primary table index of a sorted table for managing the order of table rows in accordance with the sorted primary or secondary table key. So when you append it appends as last entry not in order so it gives dump.
Hope it helps you.
Kindly let me know.
Thanks & Regards,
Vignesh Yeram