Arduino + Musical Instrument Shield

This is where I'm stuck… I'm trying to get it to work with the example code provided by Sparkfun-- replacing delay() with mills(), except it doesn't work the same. Where am I going wrong? (I combined the Sparkfun's example code with BlinkWithoutDelay).

#include <SoftwareSerial.h>

SoftwareSerial mySerial(2, 3); // RX, TX

int val = 0;



byte note = 60; //The MIDI note value to be played
byte resetMIDI = 4; //Tied to VS1053 Reset line
byte ledPin = 13; //MIDI traffic inidicator
int  instrument = 0;



// Variables will change:
long previousMillis = 0;        // will store last time LED was updated

// the follow variables is a long because the time, measured in miliseconds,
// will quickly become a bigger number than can be stored in an int.
unsigned long interval = 1000;           // interval at which to blink (milliseconds)

void setup() {
  
  Serial.begin(57600);

  //Setup soft serial for MIDI control
  mySerial.begin(31250);

  //Reset the VS1053
  pinMode(resetMIDI, OUTPUT);
  digitalWrite(resetMIDI, LOW);
  delay(100);
  digitalWrite(resetMIDI, HIGH);
  delay(100);
  talkMIDI(0xB0, 0x07, 120); //0xB0 is channel message, set channel volume to near max (127)

}

void loop()
{
  
  Serial.println("Basic Instruments");
  talkMIDI(0xB0, 0, 0x00); //Default bank GM1

  //Change to different instrument
  for(instrument = 0 ; instrument < 127 ; instrument++) {

    Serial.print(" Instrument: ");
    Serial.println(instrument, DEC);

    talkMIDI(0xC0, instrument, 0); //Set instrument number. 0xC0 is a 1 data byte command

    //Play notes from F#-0 (30) to F#-5 (90):
    for (note = 60 ; note < 70 ; note++) {
      Serial.print("N:");
      Serial.println(note, DEC);
  
// ****************************************************    
// HERE IS WHERE DELAY() IS REPLACED WITH MILLIS():

      //Note on channel 1 (0x90), some note value (note), middle velocity (0x45):
      noteOn(0, note, 60);
       unsigned long currentMillis = millis();
        if(currentMillis - previousMillis > interval) {
            
            previousMillis = currentMillis;   
              noteOff(0, note, 60);
    }
  }
    delay(100); //Delay between instruments
  }
  
  
} 
  
  
 

//Send a MIDI note-on message.  Like pressing a piano key
//channel ranges from 0-15
void noteOn(byte channel, byte note, byte attack_velocity) {
  talkMIDI( (0x90 | channel), note, attack_velocity);
}

//Send a MIDI note-off message.  Like releasing a piano key
void noteOff(byte channel, byte note, byte release_velocity) {
  talkMIDI( (0x80 | channel), note, release_velocity);
}

//Plays a MIDI note. Doesn't check to see that cmd is greater than 127, or that data values are less than 127
void talkMIDI(byte cmd, byte data1, byte data2) {
  digitalWrite(ledPin, HIGH);
  mySerial.write(cmd);
  mySerial.write(data1);

  //Some commands only have one data byte. All cmds less than 0xBn have 2 data bytes 
  //(sort of: http://253.ccarh.org/handout/midiprotocol/)
  if( (cmd & 0xF0) <= 0xB0)
    mySerial.write(data2);

}

This is what the section of the noteOn/noteOff section of Sparkfun's example code looks like:

    for (note = 60 ; note < 70 ; note++) {
      Serial.print("N:");
      Serial.println(note, DEC);
      
      //Note on channel 1 (0x90), some note value (note), middle velocity (0x45):
      noteOn(0, note, 60);
      delay(50);

      //Turn off the note with a given off/release velocity
      noteOff(0, note, 60);
      delay(50);
    }

    delay(100); //Delay between instruments
  }