I’m not seeing any obvious problems with the macro, so it’s most likely a keybinding conflict.
What key do you have the macro bound to?
Make sure that you don’t have shift-KEYBIND bound to something else in your keybinds. (Shift-1 to Shift 6 are bound to action bar switching by default, for example.)
Most number pad keys do not play well with shift modifiers on Windows. (As Windows will translate them to things like “Home” and “End” instead of the actual key.)
On macs, you can run into problems with the keypad binds as well. There’s a fix for that here.