1. Here is how to make Reason receive MIDI properly: Select the MIDI interface driver in the Midi Preferences. Make sure that You set the incoming MIDI channel in the MIDI preferences to the same channel as Your keyboard transmits on. Make sure that the MIDI cables are working and that they are properly connected to Your MIDI interface. Do not make any settings in the Advanced MIDI preferences until You are prepared to control Reason from another application or doing more advanced stuff. Put a sequencer track in focus - preferably a track that controls a Subtractor or Malstrom in order to make sure that this unit will make a sound without having to load any patches. Click to the left of the sequencer track name in order to bring up the Midi in Icon. Play on the keyboard. Not only will the unit make a sound, You will see a green activity bar flashing next to the sequencer track name as well.
2. Always check for the availability of new drivers for Your MIDI interface and the operating system that You are using on the interface manufacturers web site. Do not settle with the ones included on a CDROM in the actual interface package, chances are that these are old and obsolete. You should also make sure that any old drivers that You have already installed do not need to be un-installed prior to a new installation - if so, follow the instructions on how to do this. If You can locate new drivers, download these and install them. This applies to every operating system, there are just a few MIDI Controllers currently on the market that do not require MIDI drivers in Mac OSX.
3. A MIDI interface that has more than one MIDI In will have multiple ports available in Reasons MIDI preferences, one above the other. Make sure that You select the Port that You have connected to the MIDI Keyboard in the drop down. This also applies for some of the USB-keyboards that are equipped with a separate MIDI input/output. A Midiman Oxygen8 e.g. will have two available ports with identical names in the Reason Port selector. Make sure to try both of these.
4. Mac OS9. Be sure to install OMS before You install the drivers for Your MIDI interface. Some of the driver installations will not install the appropriate OMS drivers if OMS is not present in the system when You install the MIDI drivers. The solution to this is to first install OMS and then re-install the MIDI drivers.
5. Mac OS9. Even though the installation of the drivers went well and You may have a positive result during the Test Studio option in OMS, if the connections does not work in Reason, create a brand new OMS Setup in order to kick start OMS into action. Follow the instructions on this web page: www.propellerheads.se and do not forget to do the Add device per Port action, especially if You have a multi port MIDI interface. With some of the drivers for e.g. a MOTU Fastlane, OMS will automatically find the interface and identify it as one unit but it will not create the 2 ports that correspond to the actual MIDI inputs on the Fastlane. This is fixed by using the Add device per port function in the OMS Setup.