Remote ssh does not start effect

Hi all!
I'm running an ongoing home automation project with two Raspberry Pi's, one has Hyperion installed/connected to it. After a morning's work I figured out how to start an effect using a remote ssh connection from one rPi to another:

sshpass -p 'pass' ssh osmc@192.168.1.33 sudo hyperion-remote -p 50 -e \"Knight rider\" -d 6000 > tempoutput.txt 2>&1

This works, as I can see the effect and read the output in tempoutput.txt. However, I want to start this from within a php script. This is the (same) code:

exec("sshpass -p 'pass' ssh osmc@192.168.1.33 sudo hyperion-remote -p 50 -e \"Knight rider\" -d 6000 > tempoutput.txt 2>&1");

I can see the same output in tempoutput.txt, which would mean the effect is started, but it doesn't. The lights stay off. I'm asuming that the remote ssh does work since a ping test works fine, but I have no clue what could be the case here.
Who can help me?

Thanks for your reply. I tried both options but the problem stays the same: it works from the command line, but not from within the php file.

What kind of construction would I need to do that? I'm not used to JSON. I have a working script which activates a web stream:

exec('curl -i -X POST -H "Content-Type: application/json" -d \'{"method":"Player.Open","id":44,"jsonrpc":"2.0","params":{"item":{"file":"http://icecast.omroep.nl/radio2-bb-mp3"}}}\' http://192.168.1.33:8080/jsonrpc');

So I combined this with the JSON RPC found here to come up with this result:

exec('curl -i -X POST -H "Content-Type: application/json" -d \'{"jsonrpc":"2.0","id":1,"method":"Addons.ExecuteAddon","params":{"addonid":"script.hyperion","params":{"command":"effect", "effect":"Snake"}}}\' http://192.168.1.33:8080/jsonrpc');

I think the syntax is correct, but this doesn't work. Can you point me in the right direction on how to start an effect remotely by using JSON?

I couldn't get JSON to work since I really don't know how to send a JSON message via php.
However, I did find a (not so pretty) solution! Instead of directly executing the effect script, I placed it in a shell script that I uploaded to the remote Pi.

#!/bin/bash
sudo hyperion-remote -p 50 -e "Knight rider" -d 6000

The php file now executes the shell script using:

exec("sshpass -p 'pass' ssh osmc@192.168.1.33 sudo ./shellscriptfile");

And this works! It seems that Hyperion won't start the effect if the command comes from a remote machine - even though it outputs that the effect has started. One disadvantage though: there's a huge delay (multiple seconds) between calling the php script and the effect execution. So if there's a way to pass the command directly to the remote machine using JSON, that would still be an improvement.

In case anyone's interested: using the mobile app Tasker, Hyperion will now show the Knight Rider effect when somebody calls me on my mobile phone Now that I have Tasker and Hyperion working together, imagine the possibilities! Effects for receiving email, change of colour according to my phone's battery life, etc etc.