[Question] Could not get video output after reboot

[imbearchang]

Hi,
I use SampleVCam.plugin, without kext installed.
Every time after reboot macOS, I could not get video using OBS. But if I use QuickTime movie recording function, the plugin works well. And the weird thing is after quitting QuickTime app, and opening OBS app, OBS can get video buffer from plugin.
I've put plist into /Library/LaunchDaemons and /Library/LaunchAgents folders.
Is there anything I missed ?