MIDI input problem

my setup is M Audio Axiom 49, connected from MIDI Out into the MIDI in on a presonus firepod. Presonus firepod connected via firewire to my pc. In Reaper i have loaded my Firepod as my ASIO driver. I have recorded a few little experimental numbers with this setup. Total newbie to MIDI basically. So i have been doing research and find that i can connect my Axiom straight into my PC via USB. I want to give this a try. So in Reaper, under preferences - MIDI Device, i 'enable' both USB Axiom 1 & 2 inputs that it finds (presumably because i had connected the axiom to the usb port on my pc and Reaper picked it up). Now, if i disable the previous MIDI input, simply titled 'Axiom 49', and keep both the USB Axiom inputs enabled, i get no sound when i play the tunes, well no sound from the MIDI data anyway, the vocals on the track still work. Why's this? Apologies for my dumbass. Rabten

delete this thread 

sorry, i realise now its because my VST folder isn't being found. Please delete this thread.

nope , wrong again, with one song, it loads all the VSTs fine and allows me to use hte USB Axiom inputs only.. weird..