This may be because the Mac can not see the third MIDI input port from the ReMOTE SL (earlier versions of the ReMOTE SL OS only had 2 MIDI input ports Via USB).

The following steps should resolve this issue;

1/. Run the latest ReMOTE SL installer to make sure you have the latest OS in your ReMOTE SL.
2/. Open Audio MIDI setup. (Mac HD/Applications/Utilities/)
3/. Find the ReMOTE SL entry (in the 'MIDI Devices' section)
4/. Switch off the ReMOTE SL
5/. Highlight the ReMOTE SL entry in Audio MIDI setup, and select the 'Remove Device option'.
6/. Switch on the ReMOTE SL (If it doesn't appear automatically, select the 'Rescan MIDI' option).

The ReMOTE SL should now appear with 3 inputs and outputs, and you should be able to use Automap universal.