Application.onkey error 1004 (even with very simple code)

Hello all! This is my first post, I just registered, hopefully I won't break any forum rules.

I am trying to make application.Onkey work on my excel. I keep getting error 1004 message. I decided to try at least to make it work in a new .xlsm file with nothing in it, except this code... and I still get the error message. I really don't know what is wrong. Please help.

Private Sub Workbook_Open()
Application.OnKey "^{+}{P}", "test"
End Sub

Sub test()
ThisWorkbook.Sheets(1).Range("a1").Select
End Sub