how to take transactional log backup in sybase ase 15.7?

Hello Experts,

I want to take transactional log backup from sybase as 15.7. But when i executed the following command it got some error.

dump tran PCD to "H:\SAP_DB_Backup\PCD\PCD_dbtrans16_12_2014_backup.bkp"

I searched in net , but i didn't get a proper answer.

Kindly help😢

Regards

Praveen