Casio Keyboard that will not connect to Garage Band

but when I try to play the piano in garage band it does not work.

In what way does it not work? Don't you hear the keyboard or does it not record anything?

And how is the keyboard connected? To the USB port or are you using an interface?

If you cannot hear anything, check, the settings on your keyboard. I don't have your keyboard, but usually the problem is that the volume is set too low on the keyboard, or that the octave setting on the keyboard does not match the range of the selected software instrument track. For example, you will not here anything on a piano track, if the octave on the keyboard is "1", because the piano does not play that octave.

The Keyboard is connected to my computer though a midi to USB cable.

And that is in a midi-out plug?

You have selected a Software instrument track, when you are playing the piano? What instrument have you selected? Which octave are using on the keyboard?

Sometimes GarageBand will not play the sound at first, unless you record to the track at least once. Do you see notes in the Track editor for the track appearing, when you press the record button, before you start playing?

To check, if GarageBand is reading your keyboard at all, I'd first try to record to test track, that you can delete later. Show the Track editor while playing.

Also show the Musical Typing Window (⇧⌘K). That should mimic the keys, that you are pressing on your keybord. This way you will see what GarageBAnd is reading from the midi.

If GarageBand reads the notes, but jyou just can't hear anything, set all volume sliders to maximum, try a different instrument, try a different octave.