DIY Calculator : Keyboard Vs. Mouse?

I am creating a DIY calculator.The one in W7, I can't hardly see. Mine is much simpler and larger.I currently have buttons for numeric 0 - 9, Add, Subtract, Multiply, Divide, Clear, Enter, and Decimal Point.There is a label at the top with displays results.If I use my mouse to select the buttons, then everything works okay. However, if I use the keyboard, I get strange results.I thought it may have been my old keyboard so I changed it.No difference.If it's not in the hardware, then it's in the code.The section below is what I have for keyboard use:

Private Sub Form1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles Me.KeyPress
Ch = e.KeyChar
Select Case Ch[code]....

For each of these, there is a corresponding Button_Click even farther down in the code. Since the mouse click on the buttons on the form works properly, the problem must be above. I can't see it.