I found the cause of this problem. Scp to remote2 requires an password authentication. But ssh does not bring me the authentication request of scp, so I got "permission denied" message.
@spoon!: I'm about writing an automation script to copy files from development machine to production machine. So, all command should be in a script and be executed on local machine only.
Here is my problem again:
I need to copy files from development machine to production machine. However, production machine is not visible to development machine. Every access to production is only available via a jumpgate.
So, I thought I could ask the jumpgate to give me a shell and do a scp from that shell to copy files from development machine to production machine. But ssh failed me

Any solution for my problem (Not rsync please

)