How to save Macro as a VBA PPT Add in and use that Add In for running Macro in any PPT. Not to plug in VBA code each time.

i am testing a simple sub with MsgBox "Hello" and this macro ran fine as a ppt...So here is what I did

1. Open PPT
2. Add a new macro - with above MsgBox in VBA
3. Close VBA
4. File Save As abc.pptm
5. Close it
6. Reopen abc.pptm
7. File Save as abc.ppam
8. Open an existing ppt
9. File Options Addins - select this abc.ppam
10. Go to Developer Tab - I click on Power Point Add Ins - I see this abc in the popup as checked and selected
11. Click on Macro button in Developer Tab - nothing.
12. Press Alt F11 - no code there.

What am I doing wrong here?