works: MIDI-IN: code + schematics

Hi every one,

Today I debugging Andreas his schematics etc.
We made good progress, but got stuck later on.
As mattgilbernet said:

'm also having trouble with this. I've confirmed that midi is coming through the jack by removing the opto-isolator and putting an LED between pins 4 and 5 of the jack. I've confirmed that something is coming through the opto-isolator disconnecting RX and instead putting an LED between +5 and pin 5 of the opto-isolator. It flashes when I hit keys. Ive tried 38400 baud as well. The Arduino is just not receiving the Serial in RX. I've at least narrowed it down, can anyone provide any tips or things to try?

the LED tests show that everything is working, or at least signals are being passed, all the way up to Arduino's RX pin. At that point the Arduino seems not to recognize the signal.

We tried sending serial data from the pc to the arduino, and that worked. Arduino was able to receive that.

So the big question is:

WHY is arduino not receiving the serial data from my midi signal?
(p.s. the code never gets past the "if (Serial.available() > 0)" part)

THANKS

Titus

EDIT:
@sciguy

take a look at the schematic of the optocouper's inside on page 1
Your optocoupler has no pin 3 and no pin 6 is my guess
so you'd only need to skip the 100K Ohm resistor to ground.
The rest is the same
GL Titus