Hey, sorry, I haven't been able to reply. My specs are: Focusrite 2i2 2nd gen, a CASIO privia USB-MIDI keyboard, APU A10 7850k, 8gb ddr3 1866, RX480 8gb, and a 550W NZXT Hale82 V2 power supply. I used to have no problems with this, now all of a sudden I can't use MIDI properly, yet audio works just fine. I've uninstalled Sonar multiple times trying the 32-bit and 64-bit versions. I'd like to add that now I can't even hear it through the keyboard's speakers! 

Just to check when you press a key on the Casio Keyboard do you see the midi meter on the track you have set up in Sonar show activity? 

Yes, I can see the meter go up. I can even record a MIDI secuence if I use the sound that come with the keyboard and it will play through its speakers