Please help, my MIDI keyboard wont play in Studio One :(

Please bear with me here, i'm relatively new to studio one 3...

However, Ive set up my CASIO MIDI Keyboard exactly like in the tutorials but i cant get it to work. It plays and records perfectly fine when its just playing back the piano, but when I insert an instrument from the Browse section it doesn't play that instrument/sound, instead still playing the sound from the "piano" Keyboard.

Please help if you have any ideas on how to fix this .