well his problem is he has not configured tnsnames.ora nothing more

SGH node tnsnames.ora must have entries of SGH

if you look my previous post:

the data first travel from dev817 to dev920, i.e my session then from my session I send the data to rep817

that means dev920 must be able to connect to dev817 and rep817

if he logon to a rep817 session then rep817 must be able to see dev817 and so on

For better performance you should issue copy from one of two nodes locally not from any remote sqlplus session or the network traffic will be generate twice