Dfplayer mini serial error on Lillypad

Hi guys

I’m doing some dfplayer setting for my project with lillypad arduino.

Everything works except tiny little problem :frowning:

This is basic dfplayer mini running code

#include <DFPlayer_Mini_Mp3.h>
#include <SoftwareSerial.h>

SoftwareSerial mp3Serial(4, 3);

void setup() {
  mp3_set_serial (mp3Serial);
  mp3_set_volume (25);

void loop() {
  mp3_play (1);

I think this code is fine, It runs well on UNO.

However with Lillypad, It doesn’t work at all.

I can’t even see the light on dfpayer mini.

If there a way to solve this, help me :frowning:

I can't even see the light on dfpayer mini.

Suggest you haven't wired it up right.