pactl load-module doesnt want to set the property media.class and returns a generic message.

hi all, I am running KDE neon 5.27.6, im confused why I am receving a genaric Failure: Module initialization failed when running

<span style="color:#323232;">$ pactl load-module module-null-sink media.class=Audio/Source/Virtual sink_name=obs-mic channel_map=front-left,front-right
</span>

running

<span style="color:#323232;">$ pactl load-module module-null-sink sink_name=obs-mic channel_map=front-left,front-right
</span>

<span style="color:#323232;">Server String: /run/user/1000/pulse/native
</span><span style="color:#323232;">Library Protocol Version: 35
</span><span style="color:#323232;">Server Protocol Version: 35
</span><span style="color:#323232;">Is Local: yes
</span><span style="color:#323232;">Client Index: 52
</span><span style="color:#323232;">Tile Size: 65472
</span><span style="color:#323232;">User Name: hello-hotel
</span><span style="color:#323232;">Host Name: hello-hotel-tuff
</span><span style="color:#323232;">Server Name: pulseaudio
</span><span style="color:#323232;">Server Version: 15.99.1
</span><span style="color:#323232;">Default Sample Specification: s16le 2ch 44100Hz
</span><span style="color:#323232;">Default Channel Map: front-left,front-right
</span><span style="color:#323232;">Default Sink: alsa_output.pci-0000_0d_00.4.analog-stereo
</span><span style="color:#323232;">Default Source: obs-mic.monitor
</span><span style="color:#323232;">Cookie: ***sensored***
</span>

thanks for your help!