Default No USB Debugging popup

Hi there,

I recently bought a Lenovo Yoga 8 tablet and I'm trying to install cyangenmod on it. When I'm in USB debug mode I don't get RSA key fingerprint popup screen with always allow this computer. I've tried several drivers and launched the Android SDK and updated it, but still no luck. I've tried setting it from MTP to PTP and vice versa, but still doesn't work sadly.

cdn.androidpolice.com/wp-content/uploads/2013/02/nexusae0_Screenshot_2013-02-12-11-47-41_thumb.png

This is the promt popup I'm talking about, whatever I do I can't get this popup to come up. Any ideas why i'm not getting the popup?