Hi thatantguy,
There were a small number of Mio Alpha HRMs released that supported ANT+. You can tell whether yours is one of those by looking at the back of the unit. If it supports ANT+ there should be an ANT+ logo in the top left corner and the number should be 52P not 53P (bottom right).
It didn't make it into the product directory as the full product launch was cancelled.
Is your device an ANT+ unit?
Kat