You will never find a remote, as the Slingbox was never designed to work from a TV. But I built a Custom Remote for Panasonic TVs over at JP1 Remotes :: File Section which will probably work for you. It's quite old so I guess the installation instructions are out-of-date so use the ones at How to Install a Custom Remote onto the Slingbox – Place Shifting Enthusiasts
For future reference "... I receive the error message...." without saying what the error message was is a monumental waste of time.