Hello.
There are a couple different problems I notice from your picture.
First, it looks like you are not soldering your connections to the MP3 Trigger; you will need to solder them to ensure a good electrical connection. I typically prefer using male or female header pins so you can easily change your connections with the jumper wires.
However, before you solder, it looks like you are also mixing up the connections. There are 2 different options for triggering a track on the MP3 Trigger from a Maestro script.
The first option would be using the trigger inputs on the MP3 Trigger. The 18 input pins on the MP3 Trigger (TRIG01-TRIG18) can be used to trigger specific tracks on the microSD card by driving them low (the MP3 trigger pulls them high by default). To do this from a Maestro channel, you can configure the channel as an Output in the Channel Settings tab of the Maestro Control Center. After that, the “position” of the channel will determine if the channel outputs a high or low signal (the output is low unless the position value is greater than or equal to 1500.00 μs). So, you can use a separate Maestro channel for each trigger input you want to use by connecting the desired Maestro channel to the dedicated trigger input pin on the MP3 Trigger. Please note that you should also have a common ground between the two devices. You can read more about the trigger inputs on the MP3 Trigger under the “Using the Trigger Inputs” section of SparkFun’s MP3 Trigger hookup guide.
The second option is using the MP3 Trigger’s serial interface. This option is only applicable to the Mini Maestro controllers (i.e. not the Micro Maestro since the script commands for sending serial signals do not work with it) and it does not use any of the Maestro’s channels since it uses the UART pins instead. To do this, you would connect the TX pin from the Maestro to the RX pin on the MP3 Trigger, as well as the common ground connection. Jon’s post here has an example of what the script commands would look like to trigger a track, as well as some configuration notes. You can find more information about the MP3 Trigger’s serial commands in the “Serial Control Protocol” section of its hookup guide.
Also, please note that the tracks on your microSD card will need to be named appropriately, as described in the MP3 Trigger hookup guide.
Brandon