Assuming you're using OS 10.13 (High Sierra), it's likely you havn't enabled the KEXT.
Apple has become somewhat obsessed with security (probably a good thing at the end of the day), and when installing new drivers you have to confirm that the OS can load them.
This is covered in steps 5/6/7 of Installing iShowU Studio
The important bits:
- Go to Security & Privacy in System Preferences
- Make 100% sure the kexts are loaded! (the Allow button only shows if you've recently attempted to load a new kext)