PSCP: SFTP Server Not Accepting Password in -pw Command Line Argument

Question

I am attempting to connect to an SFTP server using PSCP through the command line. My password is passed using the -pw command line argument, yet the connection is refused and I am prompted to enter my password manually. Entering the password manually — the very same one in the -pw argument — allows the connection. Why is the password refused, and how can I get the server to accept it?

If it is relevant, the port I'm connecting to is 7834. I've already accepted the key during my first connection.

Command used:

"[myPSCPDir]\pscp.exe" -pw [myPassword] -P 7834 [myFileDir]\myFile.txt [e-mail]:/theirFolder

Message received:

Keyboard-interactive authentication prompts from server:
End of keyboard-interactive prompts from server
Access denied
Keyboard-interactive authentication prompts from server:
| password
| Password:
End of keyboard-interactive prompts from server