Alpha Tag Error

I have 2 Uniden BCD996XT and I want to provide Alpha Tags to both. It's not giving me an option to use a com port. It click on the down arrow and it says "None". One the first scanner i'm using Front Mic/ Real Tec High Definition. And the second scanner I'm using Sound Blaster X-Fi



How do I address this issue so I can run Alpha Tags.



Thank You