Hi Prakash - I could retrieve below explanation form sybase manuals.
These errors indicate a mislabeled or illegal-format archive volume. User should use offline commands to verify that the tape contains Sybase information. The following commands submitted repeatedly in order will display the beginning and ending label characters for each file on the tape:
dd if=<tape_device> bs=2048 | od -cmt
-f <tape_device> fsf 1dd if=<tape_device>
bs=2048 | od -c
Zero bytes reported from "dd" and "od" denotes no further data on the tape.