Do you have any cards already installed?
Depending on software version, look at Hardware > Modules > Analog Services Units. This will give an indication on what is programmed and installed.
For an AX it should be AX Card Chassis. Then look in Hardware > Peripheral/DSU you should see all of your installed and programmed cards.
The 24Port should be installed even if is not programmed, you then change the programming to match the installed.
Not sure of your experience level so not sure if you already looked at this.