I have a few midi interfaces I use but just discovered that Midisport devices in general are not yet compatible with OSX Yosemite, so those that rely on these interfaces should not upgrade operating system just yet. It will brick it.
There are workarounds, but way too tedious to bother with. Stay with your current operating system for the time being.
Just wanted to give those people a heads up and avoid potential dramas. Hopefully M-Audio will sort this out soon, but they don’t seem to update their drivers that often.