ssh to remote host and run a command in the back ground

Hi guru's

need your help in finding out the cause of this issue

source host > ssh -t remote hostname 'cd /app/; nohup ./RunBackup.sh
auto &'

>From the source host i am not able to execute this , where as if i
take the "-t" option out,

the script get's executed at the remote host , in the background.

Please help