I would suggest you try a SerialCommunication test, let's say @19200 bauds, then 115200 baud. If this work, then look at the USB code.

Refer to table 2-2, they recommend 15 pF. But yeah... depending the precision of your capacitor 22pF might be too high. If you have any scope handy, use a 10X probe and looks at OSC2 pin.

4MHz work also just fine.